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How to Change Tax Code in the UK - A Step by Step Guide

In the intricate fiscal landscape of the United Kingdom, tax codes stand as critical markers that determine the amount of income tax each individual or entity is obligated to pay. The tax code itself is a compact alphanumeric sequence assigned by Her Majesty's Revenue and Customs (HMRC), the UK's tax authority, reflecting the taxpayer's allowances, deductions, and reliefs. It serves a foundational role, not just in the calculation of tax, but as an indicator of an individual's tax status and eligibility for certain tax thresholds and exemptions.

How to Change Tax Code in the UK

The tax code is composed of several elements that together reveal a taxpayer's situation. Typically, the code starts with a number, which represents the total amount of tax-free income one is entitled to in a particular tax year. This figure is then followed by a letter, which provides further detail on the allowances a taxpayer can claim and any special situations affecting their tax. For instance, the standard Personal Allowance tax code for the 2023/24 tax year begins with '1257', which indicates a tax-free Personal Allowance of £12,570. This number would be followed by a letter such as 'L', denoting eligibility for the standard tax-free Personal Allowance.

Accuracy in a tax code is paramount, as any discrepancy could result in either an overpayment or underpayment of tax. An incorrect code might stem from outdated or erroneous information held by HMRC about a taxpayer's income streams, benefits, or personal circumstances. Consequently, an individual may face unexpected tax bills or receive tax refunds upon rectification of their tax code. For businesses, a mistake in the corporate tax code could lead to significant financial discrepancies affecting cash flow and compliance status.

Reasons for a change in tax code are diverse and often stem from changes in an individual's or entity’s financial or personal circumstances. An individual might acquire a new job, receive additional income such as benefits in kind or a pension, or incur work-related expenses. Other reasons include changes to state benefits, adjustments to tax legislation, or rectification of previous HMRC errors. In the case of a business, changes might include modifications in company structure, registration for VAT, or variations in taxable profits.

The ensuing consequences of an incorrect tax code reach beyond financial repercussions; they can also involve administrative burdens in the form of lengthy correspondence with HMRC to resolve issues. Given the potential for complications, taxpayers are incentivized to promptly review and adjust their tax codes whenever relevant changes in their income or personal life occur. A proactive stance in managing tax codes not only ensures the correct amount of tax is paid, but it also preempts complications that could arise from neglecting this crucial aspect of fiscal responsibility.

With such vital implications at stake, it is essential to maintain a vigilant approach to tax codes. When changes occur in one's financial circumstances, swift action must be taken to notify HMRC to guarantee that the code reflects the current reality. The process for changing tax codes has been made increasingly accessible through the use of online platforms, providing taxpayers with a more direct and less time-consuming method of keeping their tax information current. Nevertheless, understanding the nuances of one's tax code and how it pertains to individual circumstances is a prerequisite to ensuring one's financial affairs are accurately reported and appropriately taxed.

Understanding Your Current Tax Code

Understanding one's current tax code in the UK is an essential step in ensuring that the amount of tax paid is accurate. A tax code is typically issued by HM Revenue and Customs (HMRC) and is used by employers and pension providers to calculate the amount of Income Tax that should be deducted from an individual's income. Comprehending the composition of these tax codes and how they apply to individual circumstances is imperative for every taxpayer.

The Composition of Tax Codes

UK tax codes are usually made up of a series of numbers followed by a letter. Here is a breakdown of what these components represent:

Numbers in the Tax Code:

The numbers in a tax code represent an individual's tax-free income – the amount of income that one is entitled to earn in a year without having to pay tax on it. This figure is obtained by taking the tax-free Personal Allowance, subtracting any income that one has not paid tax on, and then dividing by 10.

For example, if the tax-free Personal Allowance is £12,570 (which is the case for the 2023/24 tax year), the number in your tax code would typically be '1257'. However, this number can be altered by several factors, such as owing tax from a previous year, having untaxed income, or receiving benefits in your job like a company car.

Letters in the Tax Code:

The letter in a tax code indicates the type of allowance you are receiving and any other situations that affect your tax.

  • 'L' signifies that you are entitled to the basic Personal Allowance.

  • 'M' and 'N' are used if you've transferred 10% of your Personal Allowance to your spouse or civil partner ('M') or you've received 10% of their allowance ('N').

  • 'T' could mean there are other considerations that need to be accounted for, and HMRC will review your tax code.

  • '0T' is often used when all allowances have been used up, or at the start of a new job, and HMRC doesn't have the details it needs.

  • 'BR' stands for Basic Rate, and indicates that all the income from this source is taxed at the basic rate – commonly used for a second job or pension.

  • 'D0' means all income is taxed at the higher rate, which might occur if you have a second job that pushes you into a higher tax rate.

  • 'NT' means No Tax is to be taken from this income.

Finding Your Current Tax Code

To find your current tax code, you can:

  • - Check your payslip, as it should be listed usually on the left-hand side.

  • - Look at your P45 or P60, which are given to you by your employer when you stop working for them or at the end of the tax year, respectively.

  • - Use the HMRC online service by signing into your personal tax account.

  • - Refer to the 'Tax Code Notice' letter if HMRC has sent you one.

How to Interpret Your Tax Code

Interpreting your tax code involves matching the number and letter combination with your personal situation. The number, as mentioned, represents your tax-free allowance, while the letter corresponds to your current tax situation. If your tax code ends in 'W1' or 'M1', these are emergency tax codes, and mean you'll be taxed on all income above the basic Personal Allowance – it's a temporary code usually applied when HMRC does not have enough information about your income.

It is crucial for taxpayers to ensure their tax code reflects their current situation. If you have recently gotten married, for instance, and you or your partner want to transfer some of your Personal Allowance, your tax code will change to reflect this. Similarly, if you've taken up a second job, or started receiving income from a pension, your tax code should be updated to ensure the correct amount of tax is deducted.

If you believe your tax code is incorrect, or if you have had changes to your income or benefits, you should contact HMRC. You can do this through your personal tax account, via telephone, or by writing to them. When you contact them, be prepared with your National Insurance number and any pertinent details of your income and benefits.

It's important to act quickly if you believe your tax code is wrong, as incorrect tax codes can lead to under or overpayment of tax. Regularly checking your tax code and keeping your financial details up to date with HMRC will help prevent future tax issues. Next, we will delve into the step-by-step process of altering your income tax code to ensure it accurately reflects your financial situation.

The Process of Changing Your Income Tax Code

The Process of Changing Your Income Tax Code

Changing your income tax code is a necessary step if your current code doesn't reflect your actual circumstances, as it determines how much tax is deducted from your salary or pension. To ensure you are paying the correct amount of tax, it is crucial to update your tax code when there are changes in your income, allowances, or benefits.

Identifying the Need for a Change

The first step in the process is to determine why your tax code needs to be updated. Common reasons include changes in:

  • - The amount of income you receive, such as a new job or a different salary.

  • - Taxable company benefits, like a company car or health insurance.

  • - Other income, for example, rental or investment income that is not automatically taxed.

  • - Personal circumstances, such as marriage, divorce, or the transfer of a portion of your Personal Allowance to or from a partner.

Communication Channels

HM Revenue and Customs (HMRC) provides several communication channels through which you can inform them of the necessary changes to your tax code. Here are the primary methods:

Online Through Your Personal Tax Account

The most efficient way to change your income tax code is through your personal tax account. This digital service allows you to:

  • - View your current tax code and income details.

  • - Update your income estimates and report changes affecting your tax code.

  • - Send a message directly to HMRC regarding any discrepancies.

You will need a Government Gateway user ID and password to access your personal tax account. If you do not already have these, you can create them by providing your National Insurance number and proving your identity using valid UK documents or information tied to your financial records, such as a UK passport, payslip, or P60.

By Telephone

If you prefer to speak with an HMRC representative, you can contact the Income Tax General Enquiries line. It's important to have your National Insurance number and other relevant income details ready when you call.

Telephone:0300 200 3300

Outside UK:+44 135 535 9022

Opening times:

Monday to Friday: 8am to 6pm

Closed on weekends and bank holidays.

By Post

In specific scenarios, you might need or prefer to write to HMRC. This is less common due to the speed and efficiency of digital and telephone services, but it is still a valid option if needed. Send post to:

Pay As You Earn and Self Assessment

HM Revenue and Customs


United Kingdom

Required Information and Documents

When contacting HMRC to change your tax code, ensure you have the following information at hand:

  • - Your National Insurance number.

  • - Details of the change in your income or circumstances.

  • - The date the change occurred.

  • - Your current tax code.

  • - Documentation that supports the change, such as payslips, P60, or P11D, which details benefits and expenses.

How to Report a Change

Online Method

1. Sign in to your personal tax account.

2. Navigate to the 'Check your Income Tax' section for the current tax year.

3. Review your current tax code and income details.

4. Follow the prompts to 'Tell HMRC about changes'.

5. Enter the relevant details about your income change or new circumstances.

Telephone Method

1. Call the Income Tax General Enquiries line.

2. Verify your identity with your National Insurance number and personal information.

3. Discuss your current tax code and the reasons for the change with the HMRC representative.

4. Follow their guidance to provide necessary information and documentation.

Postal Method

1. Write a letter to HMRC detailing your National Insurance number, the change in your circumstances, and your contact details.

2. Include copies (not originals) of any supporting documents.

3. Send it to the appropriate address for income tax enquiries, which you can find on the HMRC website or through your personal tax account.

What Happens Next?

After you have reported the changes, HMRC will review the information. If they require additional information, they may contact you. Otherwise, they will issue a new tax code that will be sent to you and your employer or pension provider.

Expected Timelines

When you report a change to your tax code online or via telephone, HMRC typically processes the updates within a few weeks. It can take longer if you send your request by post. Once HMRC updates your tax code, you will receive a new tax code notice (P2), and your employer or pension provider will be notified so they can apply the new code to your income.

In the case that you overpaid taxes due to an incorrect tax code, HMRC would automatically adjust your tax for the current year and may refund any overpayment. Similarly, if you underpaid, they would inform you of the amount and how it will be collected, usually by adjusting your tax code in the next tax year.

Keeping Track of Your Tax Code

It's essential to regularly check your tax code, especially after any change in your income or circumstances, to make sure it accurately reflects your tax position. Your payslip is an excellent place to keep an eye on your code and ensure that the changes have been applied correctly.

This proactive approach to managing your tax code can prevent discrepancies that may lead to overpayment or underpayment of tax. Moving forward, businesses also have to maintain accurate tax records, and this includes ensuring their corporate tax codes are up to date. The following section will explore how businesses can alter their corporate tax codes, dealing with the processes involved, including how to engage with the Corporation Tax office and utilize the HMRC online services.

Updating Corporate Tax Codes

For businesses, staying compliant with tax laws is fundamental, and that involves ensuring that the corporate tax code reflects the company's current financial situation. Unlike personal tax codes, corporate tax codes refer to the system that governs how a corporation is taxed on its profits, rather than a specific alphanumeric code assigned to an individual. It is imperative for companies to update their tax records with Her Majesty's Revenue and Customs (HMRC) if there are changes in their business structure, income sources, allowances, or other relevant circumstances that might affect their tax liabilities.

Recognizing the Need for a Change

The most common reasons a business may need to update its corporate tax information include:

  • - Change in registered office address or business name.

  • - Significant alterations in business activities or trade.

  • - An increase or decrease in profit forecasts.

  • - Acquisition or disposal of subsidiary companies.

  • - Changes in accounting periods or practices.

Any of these circumstances can lead to adjustments in the amount of tax the company is obliged to pay, and failure to report these changes might result in financial penalties or incorrect tax payments.

Accessing HMRC's Online Services

HMRC's online services provide a streamlined process for managing corporate tax affairs. To start, a business must have a Government Gateway account, which serves as a secure online portal for interacting with HMRC. If your business does not have an account, it can register for one on the HMRC website by providing the necessary details such as the company's Unique Taxpayer Reference (UTR) and the company registration number (CRN). You can also ask the HMRC chatbot.

Once registered and logged into the Government Gateway, businesses can access HMRC's online services for corporations, including:

1. Viewing Corporate Tax Liabilities:

Businesses can view their current tax liabilities, payments, and any reliefs or credits applied. This real-time information can help companies assess if their tax code needs updating.

2. Reporting Changes:

If a change has occurred, the business can report it directly through the online service. For instance, changing the registered address is a straightforward process where the business updates the address fields and submits the change, which is then processed by HMRC.

3. Submitting Corporate Tax Returns:

Companies can submit their tax returns online, which can include modifications to tax computations due to changes in corporate structure or profits.

4. Paying Tax Due:

The online portal also facilitates the payment of any corporation tax due. This system ensures that payments are made on time and records are kept up to date.

Steps for Updating Corporate Tax Information

When a business identifies the need to update its corporate tax details, the following steps should be taken:

1. Review Current Information:

The company should begin by reviewing its current corporate tax information as listed with HMRC. This includes checking the corporation tax reference number, registered address, contact details, and any associated companies or charities.

2. Gather Supporting Documentation:

Depending on the nature of the change, the business may need supporting documentation. For example, if there is a change in the company’s trade, relevant contracts, board minutes, or financial forecasts should be prepared.

3. Access HMRC Online Services:

Next, the company should sign into the HMRC online services through the Government Gateway. If it's the first time using the service, the company's UTR and CRN will be required.

4. Navigate to the 'Report Changes' Section:

Within the online services portal, there is a section specifically for reporting changes to corporate tax details. Select this option to begin the update process.

5. Input New Details:

Enter the new information as prompted by the online forms. Care should be taken to ensure accuracy as this information directly affects corporate tax responsibilities.

6. Review and Submit:

Before finalizing the update, review the details thoroughly to prevent errors. Once verified, submit the changes to HMRC.

7. Receive Confirmation:

HMRC will usually send an electronic confirmation that the changes have been recorded. This confirmation is important and should be kept for your records.

Updating Accounting Periods

One of the more complex changes that a business might need to report is a change in accounting periods. This may occur if a business decides to extend or shorten its financial year for strategic reasons. The process involves notifying HMRC of the new accounting period dates and may result in a change in the due dates for tax payments and filings. This is done through the online service by selecting 'Change your company details' and then 'Accounting period'.

Communication and Support

If clarification or support is needed at any point in the process, HMRC provides assistance through dedicated helplines and online resources. Detailed guidance for each step can be found on the HMRC website or by contacting the Corporation Tax office. Additionally, it's important to note that any changes to corporate tax details can affect other areas of taxation, such as VAT or PAYE, so businesses should consider the wider implications of their updates.

By staying vigilant and proactively managing their tax records, businesses can help ensure compliance with UK tax regulations and maintain an accurate representation of their tax liabilities with HMRC. The online services provided by HMRC play a vital role in facilitating this process, allowing for efficient and straightforward management of corporate tax affairs. With these resources at their disposal, businesses can focus more on their operational activities with the confidence that their tax obligations are properly addressed.

Adjusting VAT Registration Details

Understanding VAT Registration and Tax Codes

Value Added Tax (VAT) is a consumption tax placed on a product whenever value is added at each stage of the supply chain, from production to the point of sale. VAT-registered businesses collect this tax on behalf of HM Revenue and Customs (HMRC) and it is crucial that businesses maintain accurate VAT records and registration details. Tax codes for VAT purposes refer to the various rates and categories that goods and services are classified under, such as standard (20%), reduced (5%), or zero-rated (0%). The accuracy of these classifications can affect a business's VAT liability.

Recognizing the Need for Update

VAT registration details must be kept current. Events necessitating an update to VAT registration details could include changes to business contact details, principal place of business, the nature of business and goods sold, or a significant change in turnover.

Initiating the Change Process

The first step in the process is to determine whether the change affects the VAT taxable turnover to the extent that it surpasses or falls below the VAT threshold, which, as of the last reported year, was set at £85,000. If this threshold is crossed, it can mean either compulsory registration for businesses not already registered or deregistration for those no longer eligible.

Online Services for VAT Updates

Most VAT registration details can be updated through HMRC's online services. To access these services, businesses must have a Government Gateway account, which they likely already have from the time of VAT registration. If not, they will need to sign up by providing necessary business details and information to verify their identity.

Steps for Updating VAT Details Online

1. Log In to Government Gateway:

The business representative needs to sign in to their Government Gateway account, which is linked to their VAT online account.

2. Navigate to the VAT Section:

Once logged in, navigate to the VAT section where there is an option for ‘Change registration details’.

3. Complete the Relevant Sections:

Online forms are available for various changes, including business name or address, bank details, and business contact numbers. These forms are straightforward and guide the user through the update process, ensuring all relevant fields are completed.

4. Submit the Changes:

After reviewing the changes to ensure accuracy, the representative can submit them electronically. HMRC will process these changes and update their records.

5. Receive Confirmation:

A confirmation of the changes will be sent, which should be kept for business records. HMRC also updates the business’s VAT certificate, which is available to view and print in the VAT online account.

Changes That Require Additional Action

Some changes will necessitate further action beyond just updating details:

VAT Group Changes:

For businesses that are part of a VAT group, changes to the group composition must be reported using the VAT 56 form.

Transfer of Going Concern (TOGC):

When a business is sold and the buyer is continuing the same business, a TOGC may apply, which affects VAT registration. This requires the VAT 68 form to be completed to request a transfer of the VAT registration number.

Changes in Legal Structure:

If a business changes its legal structure, such as from a partnership to a limited company, it may need a new VAT registration, and the previous registration will need to be cancelled.

Communicating With HMRC Directly

In certain situations, it may be necessary to contact HMRC directly:

- By Phone:

HMRC has a VAT helpline for businesses that need assistance with changes. Calling the helpline can also be a quicker way to address urgent adjustments or clarify complex changes.

- By Post:

For certain changes or if advised by HMRC, written notification may be required. Forms and written communication should be sent to the address provided on the HMRC website or the form instructions.

Special Circumstances

In some instances, businesses might find that their VAT taxable turnover only exceeded the VAT threshold temporarily. In these cases, a business can apply for a registration 'exception'. This involves writing to HMRC with evidence showing why the business believes its VAT taxable turnover will not exceed the deregistration threshold of £83,000 in the next 12 months.

Keeping Records

Businesses must keep records of any changes to their VAT registration details for at least six years, as per the VAT record-keeping requirements. This is important not only for compliance but also for reference in case of future queries or audits by HMRC.

Dealing with Other Relevant Taxes

Apart from income tax, corporate tax, and VAT, there are other taxes to consider, such as National Insurance Contributions, Capital Gains Tax, and Inheritance Tax. This chapter will cover the basics of these taxes and how to ensure tax codes and details are up to date for each.

Dealing with Other Relevant Taxes

National Insurance Contributions

Overview of National Insurance

National Insurance Contributions (NICs) are payments made by employees, employers, and the self-employed to qualify for certain state benefits, including the State Pension. NICs are not strictly a tax, but they function similarly in that they are a compulsory contribution and are governed by HMRC. National Insurance is calculated based on earnings and employment status, with different classes of contributions depending on the circumstances.

National Insurance Number and Code

Each individual who pays National Insurance is issued a National Insurance number—a personal account number. It's important to note that while the National Insurance number remains the same throughout an individual's life, the category letters (which are effectively the 'tax code' for National Insurance) can change./

Changing National Insurance Category Letters

An individual's National Insurance category letter may change due to varying employment situations. Here's what to do:

1. Assess the Employment Situation: Determine why a category letter change is necessary—this could be due to starting a new job, becoming self-employed, or reaching State Pension age.

2. Notify the Employer: If employed, inform the employer of any circumstance change that may affect the National Insurance category. The employer is usually responsible for updating this through their payroll software.

3. Self-Assessment: For the self-employed, it is important to select the correct National Insurance category when filling out a Self-Assessment tax return.

4. Contact HMRC: If there are doubts about the correct National Insurance category, it's advisable to contact HMRC directly for clarification.

5. Keep Records Updated: Whenever there's a change in the employment situation, update personal details with HMRC to ensure the National Insurance record is accurate.

This can affect future benefit entitlements.

Capital Gains Tax

Understanding Capital Gains Tax (CGT)

CGT is a tax on the profit when you sell (or 'dispose of') something (an 'asset') that has increased in value. It is the gain you make that is taxed, not the amount of money you receive. Some assets are tax-free and you also do not have to pay CGT on the sale of your main home usually.

Knowing When to Update CGT Details

If there have been any changes that might affect CGT calculations—such as a change in residential status, disposals of assets, or changes to the assets themselves—it is necessary to update CGT details.

Steps for Updating CGT Information

1. Report Disposals: If an asset subject to CGT has been disposed of, report the disposal to HMRC. This can often be done through the Real Time Capital Gains Tax service or on a Self-Assessment tax return.

2. Record Keeping: Maintain detailed records of the purchase and sale of assets, including any improvements that may affect the base cost for CGT calculations.

3. Review Annual Exempt Amount: Keep track of the profits on disposals across the tax year and ensure they do not exceed the annual tax-free allowance. If they do, update the necessary records and report the gain.

4. Seek Professional Advice: With CGT being a complex area with potential reliefs and exemptions, it may be wise to consult a tax advisor to ensure all changes and updates are accurately recorded and reported.

Inheritance Tax

Overview of Inheritance Tax (IHT)

IHT is a tax paid on an estate (the property, money, and possessions) of someone who has died. There's normally no Inheritance Tax to pay if either the value of the estate is below the £325,000 threshold or if everything above the £325,000 threshold is left to a spouse, civil partner, charity, or a community amateur sports club.

Updating Details for IHT

IHT details would typically need to be updated after a person's death by the executor or administrator of the will. The following steps should be taken:

1. Estate Valuation: Determine the value of the estate to assess whether it exceeds the IHT threshold.

2. Notify HMRC: If the estate is above the threshold, fill out an IHT400 form and send it to HMRC, along with any relevant documentation to justify the valuation.

3. Pay Any IHT Due: Calculate and pay any IHT due on the estate. This should be done within six months after the end of the month in which the person died, to avoid additional interest and penalties.

4. Update Estate Records: Keep thorough records of how the estate's value was calculated, the forms submitted, and the correspondence with HMRC.

Special Situations

In certain cases, such as when gifting property or other assets before death, it's essential to keep detailed records and update HMRC if necessary, as these can affect the Inheritance Tax liability of the estate.

Reporting Changes for All Taxes

Across all these taxes, maintaining accurate records and promptly reporting any changes are essential steps to ensure compliance and avoid penalties. For National Insurance, Capital Gains Tax, and Inheritance Tax, the mechanisms to report changes will typically involve the Self-Assessment system, direct communication with HMRC, and proper adherence to tax return deadlines and requirements.

In situations where you are uncertain about how changes in circumstances affect tax liabilities or which forms are needed, contacting a professional tax advisor or HMRC directly is advisable to obtain accurate guidance and ensure that one's tax

responsibilities are met correctly.

Common Issues and Troubleshooting in changing a tax code

Common Issues and Troubleshooting

Understanding Emergency Tax Codes

Issue: A common issue faced by taxpayers is being put on an emergency tax code, which typically happens when HMRC does not have enough information about a taxpayer's income. This can result in overpayment of taxes.

Solution: To resolve an emergency tax code, you should inform HMRC about your current income and job details. This can be done through your personal tax account online or by calling HMRC directly. Once they update your records, they will issue a new tax code to your employer.

Mismatched Personal Details

Issue: Discrepancies in personal details, such as name, address, or date of birth, can lead to incorrect tax code assignments.

Solution: Ensure all your personal information is current and accurately reflected in HMRC’s records. If there are any errors, you can update your details through the online personal tax account or by contacting HMRC.

Changes in Employment

Issue: Starting a new job or having multiple jobs at once can complicate tax codes, as each employer might be applying the wrong tax code, leading to an over or underpayment of tax.

Solution: If starting a new job, provide your P45 to your new employer to help ensure the correct tax code is used. If you have multiple jobs, check with HMRC to allocate your Personal Allowance efficiently across your tax codes.

Tax Code Adjustments Post Retirement

Issue: Retirees may encounter issues when pensions are taxed incorrectly because of an outdated tax code.

Solution: Retirees should review any private or state pension statements and contact the pension provider or HMRC if the tax deducted seems incorrect. Updating your employment status to retired in your personal tax account can also prompt a tax code review.

Incorrect Allocation of Allowances and Reliefs

Issue: Taxpayers who are eligible for allowances (like marriage allowance) or reliefs (such as for charitable donations) might find these are not reflected in their tax code.

Solution: Ensure you inform HMRC about your eligibility for any allowances or tax reliefs. HMRC can then adjust your tax code accordingly, often backdating any changes to the start of the tax year.

Coding Out Underpayments

Issue: If HMRC tries to recover an underpayment from a previous year through your tax code, you may be taxed more than expected.

Solution: If you believe there is a mistake, or if paying the underpayment via your tax code is financially burdensome, contact HMRC. They may be able to spread the repayment over a longer period.

Self-Employment and Tax Codes

Issue: Self-employed individuals might find their tax code does not reflect their current business situation, particularly if they have recently shifted from employment to self-employment.

Solution: Notify HMRC of the change in your employment status. As a self-employed person, you will typically pay taxes through Self Assessment rather than a tax code, but you may still have a tax code if you have other income taxed at source.

Implications of Benefits in Kind

Issue: Benefits in kind, such as a company car or medical insurance, can alter your tax code, as these need to be taxed accordingly.

Solution: Check that HMRC has accurate information regarding any benefits in kind. P11D forms, which detail these benefits, should be correctly filled out by your employer and submitted to HMRC.

Receiving Foreign Income

Issue: UK residents with foreign income may have issues with incorrect tax codes if this income is not reported accurately.

Solution: Use the ‘foreign’ section in the Self Assessment tax return to report foreign income or gains. If you’re not in Self Assessment, you can still inform HMRC through your personal tax account or by contacting them directly.

Duplicate Records

Issue: HMRC may hold duplicate records for a taxpayer, leading to incorrect tax codes being issued.

Solution: If you suspect HMRC has duplicate records for you, contact them to rectify the situation. You will need to provide sufficient information to merge the records and correct your tax code.

Inherited Income and Assets

Issue: Beneficiaries of an inheritance may not know how to update their tax code to reflect the additional income or assets they receive.

Solution: If you've inherited assets that generate income, such as property or investments, inform HMRC so that they can adjust your tax code. IHT400 forms are used to report inherited estates to HMRC and might lead to adjustments in your tax code if you receive income from the estate.

Checking and Understanding Tax Code Notices

Issue: Taxpayers often receive tax code notices that they do not understand, leading to confusion about their taxation.

Solution: Taxpayers should carefully read the explanations provided in P2 tax code notices. If the notice is unclear, you can use the HMRC tax checker tool or contact HMRC for a breakdown of how your tax code was calculated.

Handling Overpaid Tax

Issue: Taxpayers often struggle with how to claim back tax that they have overpaid due to an incorrect tax code.

Solution: If you have overpaid tax, HMRC will usually correct this by changing your tax code to refund the amount overpaid during the current tax year. If the overpayment relates to a previous tax year, you may need to claim a refund. You can do this through your personal tax account or by completing form P50 if you're not working, or P53 if you've stopped working part-time.

Dealing with Tax Code Changes Due to Debt Collection

Issue: Sometimes, HMRC may adjust your tax code to collect other outstanding debts, such as unpaid tax or benefit overpayments.

Solution: If your tax code has been changed for this reason, and you believe it to be incorrect, or if the repayments are too high, contact HMRC. You might be able to arrange an alternative repayment plan.

These issues only represent some of the many questions and problems that may arise when dealing with tax codes. It is recommended to keep personal and income details up to date with HMRC to avoid most issues and to check your tax code regularly, especially if your circumstances change. If in doubt, professional advice from a tax advisor or direct communication with HMRC can help resolve any discrepancies and ensure you are on the correct tax code.

Case Studies: Examples of Changing Tax Codes

Case Study 1: Switching to Self-Employment


Jane had been working as a marketing manager for a large corporation for 10 years. In April 2023, she decided to leave her job and start her own marketing consultancy business. Having always been an employee, Jane's tax was previously managed through PAYE (Pay As You Earn), and she was unsure how her tax code and responsibilities would change with her new self-employed status.

Key Steps:

1. Registration as Self-Employed:

Jane registered as self-employed with HMRC, which is the first step for anyone starting a business. This ensured that she was set up for Self Assessment rather than PAYE.

2. Updating HMRC:

Using her personal tax account, Jane updated HMRC about her change in circumstances. She informed them about her cessation of employment and the start of her self-employment, ensuring her tax records reflected her new income source.

3. National Insurance Contributions:

As part of her Self Assessment registration, Jane also arranged to pay Class 2 and Class 4 National Insurance Contributions, which are necessary for the self-employed.

4. Self Assessment Tax Returns:

Jane kept meticulous records of her income and expenses as advised by HMRC, which would be necessary for completing her Self Assessment tax return.


Understanding Tax Deductible Expenses:

Initially, Jane found it challenging to determine which expenses were tax-deductible. She consulted the HMRC guidelines and eventually sought advice from an accountant to ensure accuracy.

Cash Flow Management:

Accustomed to receiving a regular monthly salary, Jane had to adjust to the irregular income flow of self-employment and plan for her tax payments, which were no longer automatically deducted.


  • Jane successfully transitioned to self-employment and completed her first Self Assessment tax return by the deadline, avoiding any penalties.

  • She was able to claim tax relief on eligible business expenses, reducing her taxable income.

  • By the following year, Jane was well-versed in her new tax obligations, and her business was thriving with a clear financial overview.

Case Study 2: Multiple Sources of Income


Ali is an engineer with a full-time job, but he also has a passion for photography and earns income from selling his pictures online. He receives royalties from a book he authored, and he has a small rental property. Managing multiple income streams meant his tax code often needed adjustments to prevent over or underpayment of tax.

Key Steps:

1. Communicating with HMRC:

Ali used the online service to inform HMRC about his multiple income sources. He had to ensure all income was declared, which included his salary, rental income, royalty payments, and profits from his photography sales.

2. Allocation of Personal Allowance:

Ali worked with HMRC to allocate his Personal Allowance effectively against his various income streams. This helped optimize his tax code and minimize overpayment of tax.

3. Receipt of P45 and P60 Forms:

Each tax year, Ali ensured that he received and kept his P45 form from any employment he left and his P60 form from his current employer. These documents were crucial for providing accurate income figures for his tax records.


Complexity of Multiple Incomes:

The complexity of having several sources of income meant that Ali's tax affairs were more complicated than the average taxpayer. Keeping records and understanding how much tax was due from each source was challenging.

Changing Tax Codes:

Ali experienced fluctuations in his various income sources, which occasionally led to his tax code being updated multiple times within a tax year.


  • Ali's proactive approach to managing his tax affairs led to a stable and accurate tax code that reflected his actual income.

  • He benefitted from tax planning advice, which maximized the efficiency of his Personal Allowance and other tax reliefs.

Case Study 3: Incorrect Tax Code Due to HMRC Error


Sophie had been working at the same company for five years. After receiving her April payslip, she noticed that her tax code had unexpectedly changed, resulting in a higher tax deduction than usual. Concerned about the sudden increase in her tax payments, Sophie decided to investigate.

Key Steps:

1. Review of Tax Code Notice (P2):

Sophie reviewed her P2 tax code notice from HMRC and compared it with her previous tax information. She realized that the code did not accurately reflect her salary or tax-free allowance.

2. Contacting HMRC:

Sophie called the HMRC helpline to query her tax code. She was prepared with her National Insurance number, current tax code, and details of her income and employment.

3. HMRC’s Correction:

After reviewing her information, HMRC acknowledged the error in her tax code and issued a corrected code to Sophie's employer.


Understanding the Correction:

Sophie initially found it difficult to understand the details of the tax code correction. She needed clarification from the HMRC representative about how the change would affect her future pay and what to expect regarding any overpayment refund.


  • HMRC updated Sophie's tax code, and her employer adjusted her tax deductions on the next pay cycle.

  • Sophie received a tax refund for the overpayment she had made in the first month, which was processed through her wages.

Each of these case studies demonstrates the importance of active engagement with one's tax affairs and the necessity of promptly addressing changes in circumstances with HMRC. Accurate record-keeping and clear communication with the tax authority help to ensure that tax codes are correctly assigned and that taxpayers do not overpay or underpay their taxes.

Required Forms and Online Portals in changing tax code

Required Forms and Online Portals

To ensure the accuracy of tax codes and the smooth management of tax affairs, knowing which forms to fill and online portals to use is essential. The following sections detail the specific forms and online resources available for taxpayers and businesses to use when updating their tax codes in the United Kingdom.

For Individuals: Updating Personal Tax Codes

1. Personal Tax Account on GOV.UK:

Every individual taxpayer can manage their tax code using their personal tax account, which is an online service provided by HMRC. To access this service, one must create or sign in with their Government Gateway user ID and password.

  • - Check your current tax code and Personal Allowance.

  • - Report changes affecting your tax code.

  • - Update details of your income.

  • - View estimated income and tax details.

  • - Notify HMRC about changes to your employment or pension provider.

2. Tax Code Query by Phone:

For individuals preferring to communicate via phone, the Income Tax: General Enquiries hotline allows taxpayers to discuss their tax code directly with an HMRC representative.

  • Contact: HM Revenue & Customs - Telephone: 0300 200 3300.

  • Required Information: National Insurance number and details of the change needed in the tax code.

For Employers: Handling Employee Tax Codes

3. PAYE Online for Employers:

Employers need to manage employees' tax codes through the PAYE Online portal. The system enables employers to report to HMRC about their employees' tax codes and other relevant payroll information.

  • - URL: [PAYE Online for employers - GOV.UK](

  • - Required Actions:

  • - Submit reports about new and leaving employees (P45, P46).

  • - Update tax code notices (P6, P9).

  • - Communicate any errors in tax codes as indicated by employees.

For Businesses: Corporate and VAT Tax Codes

4. HMRC Online Services for Corporation Tax:

Businesses dealing with corporate tax will use the HMRC online service to submit their Company Tax Return (CT600) and to ensure that details about their tax code and payments are current.

  • - URL: [Corporation Tax - GOV.UK](

  • - Required Information: Company's Unique Taxpayer Reference (UTR) and Government Gateway credentials.

  • - Functions: Submit corporate tax returns and track payments.

5. VAT Online Services:

Businesses registered for VAT must update any change in their circumstances through the VAT online service, which could include changes in business details affecting the VAT tax code.

- Register for VAT.

- Change your VAT registration details.

- Submit VAT Returns.

- Pay VAT.

For Special Situations: Other Tax Codes and Issues

6. Self-Assessment Tax Return:

Self-employed individuals and those with other forms of untaxed income will need to complete a Self-Assessment tax return, which may result in changes to their tax code based on the income reported.

7. Capital Gains Tax:

For those who need to report a capital gain, for instance, from selling property or shares, it's necessary to inform HMRC through the Self-Assessment system or by the Report Capital Gains Tax online service.

8. Inheritance Tax:

To deal with Inheritance Tax (IHT), relevant forms such as IHT205 or IHT400 may be required to assess the value of an estate and report it to HMRC.

Accessing HMRC Forms for Specific Circumstances

For those who require physical forms for various tax-related issues, including changes to tax codes, HMRC provides a comprehensive list of printable forms:

Whether managing personal tax codes, operating payroll for employees, or handling business tax affairs, the above resources and forms provide the necessary avenues to maintain accurate and updated tax information with HMRC. It's vital to use these tools proactively to anticipate and address any tax issues effectively.

Conclusion and Next Steps

The process of changing one's tax code in the UK, while systematic, can often be nuanced, with various considerations to be made at each step. Throughout this guide, we have laid out the framework for understanding the intricate tapestry of tax codes and the respective routes to take in order to adjust them. From recognizing the components of a personal income tax code to navigating corporate tax adjustments, the guide has aimed to furnish you with the tools and knowledge necessary to ensure your tax affairs are accurate and up-to-date.

Beyond merely understanding the current tax code, it is imperative to be proactive about monitoring any changes to your financial situation that could influence your tax code. Whether it is a change in employment, varying income levels from year to year, or alterations to tax legislation, staying vigilant about these variables will aid in preempting discrepancies. It is also worth mentioning that a change in tax code does not exclusively fall on the individual; employers play a crucial role in implementing the correct tax codes through the PAYE system. Clear communication with your employer is vital to prevent and resolve any issues swiftly.

For those in business, whether dealing with VAT or corporate tax affairs, ensuring that the business's tax code aligns with its current structure and activities is equally paramount. Regular reviews of your business's tax profile and prompt updates in response to structural changes, such as mergers, acquisitions, or shifts in the business model, will help maintain compliance and avoid potential fines or penalties.

For all taxpayers, the ability to articulate and rectify errors through the various channels—be it the personal tax account, contacting HMRC directly, or using the appropriate forms—is a crucial element in managing tax codes. By providing a compendium of resources, including the necessary HMRC online services, this guide encourages self-sufficiency in taxpayers, enabling them to initiate tax code changes autonomously.

Equipped with the strategies and methods to address tax code alterations, it is also advisable to adopt a routine check of your tax code. This can be facilitated by setting calendar reminders to review your tax code at the beginning of each tax year, or any time there is a significant life event affecting your tax situation. These regular checks will help in catching any errors or adjustments required in a timely fashion.

In light of the dynamic nature of tax legislation and personal circumstances, keeping abreast of the latest tax news is beneficial. Subscribing to tax bulletins, consulting tax professionals, or engaging in forums can provide insights into emerging tax trends and issues. This active approach to tax code management not only helps in mitigating risks but also maximizes your potential to benefit from any tax allowances or reliefs that may be applicable.

The digital era has ushered in a suite of online tools and services which can be leveraged to streamline the process of tax code changes. With portals like the PAYE Online for employers, the VAT Online services, and others, these platforms facilitate quick and secure interactions with HMRC. Nonetheless, taxpayers must ensure the security of their personal information and be cautious of potential scams, always accessing HMRC services through official channels.

In the instances where taxpayers encounter challenges or complex situations that demand expert advice, it is worthwhile to consult with a tax professional or accountant. They can offer tailored guidance, navigate the complexities of the tax system, and ensure that your actions are in line with current tax laws and regulations.

For self-employed individuals and those with multiple sources of income, keeping thorough records and evidence of earnings and tax payments is another layer of due diligence that should not be overlooked. Efficient record-keeping not only aids in substantiating any changes in tax codes but also proves invaluable during tax audits or when discrepancies arise.

As we navigate the nuances of the UK's tax system, this guide should serve as a comprehensive resource to not only assist in altering tax codes when necessary but also to ensure an ongoing alignment of tax affairs with personal or business circumstances. Being methodical, vigilant, and informed will place taxpayers in good stead to manage their tax codes effectively. Remember, an accurate tax code is not just about compliance; it’s about optimizing your tax position to reflect your actual financial situation.


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