Grossing Up Explained: Why A ‘Tax-Free’ Legacy Can Increase The Estate’s IHT
Grossing Up Explained: Why a "Tax-Free" Legacy Can Increase the Estate's IHT
Leaving a legacy "free of tax" in a will does not reduce the Inheritance Tax (IHT) bill on an estate. In many cases it does the opposite. Where the residue of an estate is left to a spouse, civil partner or charity, a tax-free gift to anyone else forces HMRC's grossing up calculation, which can increase the total IHT payable for the 2026/27 tax year and shrink what the exempt beneficiary actually receives. This is one of the most misunderstood mechanics in UK estate planning, and it catches out well-intentioned will drafting more often than most people realise.
I still see this most often in home-made wills and in wills drafted years ago and never reviewed. A testator wants to be generous to a friend, a carer, or a niece who would not otherwise benefit from the nil rate band, so the will says something like "I give £50,000 free of tax to Helen Marsh." It reads as an act of kindness. What it actually does, if the rest of the estate passes to a spouse or a charity, is quietly increase the tax bill for everyone else.
What "Grossing Up" Actually Means
A "free of tax" or "tax-free" legacy is a specific gift where the beneficiary is guaranteed to receive the full stated sum, with any IHT due on that legacy paid out of the rest of the estate rather than deducted from the gift itself. The beneficiary is protected from tax. Somebody else in the estate is not.
Grossing up is the calculation HMRC requires when that arrangement collides with an exemption elsewhere in the estate. Rather than simply charging 40% on the legacy and moving on, the legacy has to be treated as if it were larger than the stated amount, so that once notional tax is deducted from that larger, "grossed-up" figure, the beneficiary is still left with exactly what the will promised them. The knock-on effect is that more of the estate is drawn into the tax calculation, and the residuary beneficiary, often a spouse or a charity, ends up with less.
According to HMRC's guidance on working out what part of an estate pays Inheritance Tax, grossing up applies specifically where the value of an estate is uncertain or thresholds may change, and a testator chooses to leave a gift "tax free" so the beneficiary receives a fixed amount regardless. HMRC then applies grossing up to work out the true taxable value of the estate.
Leaving a legacy "free of tax" in your will can unintentionally increase your estate's overall Inheritance Tax (IHT) bill and significantly reduce the inheritance left to an exempt spouse, civil partner, or charity through HM Revenue & Customs' statutory "grossing up" calculation. This interactive explainer by Pro Tax Accountant reveals the true financial cost of tax-free legacies, clearly contrasting common drafting assumptions with the actual statutory rules under section 38 of the Inheritance Tax Act 1984. To explore your position, simply use the interactive sliders and options to tailor the estate value, available Nil Rate Band, and legacy amount to your circumstances; the live visual comparison will immediately demonstrate how the tax burden shifts, what each beneficiary actually receives, and how to safeguard your testamentary intentions before your will is finalised.
When Does Grossing Up Actually Bite?
It does not apply to every free-of-tax gift. Two conditions need to be present at the same time. HMRC's own guidance on the Inheritance Tax grossing up calculator confirms both are required: someone who is liable to Inheritance Tax (a chargeable beneficiary) has been left a gift free of tax in the will, and the residue of the estate, or part of it, is exempt from Inheritance Tax.
If both a friend's legacy and the residue are chargeable (say, everything passes to adult children), there is no grossing up problem. The tax on the friend's legacy simply comes off the top of the residue in the ordinary way, and the children's inheritance falls by the tax amount. Nobody's exemption is being protected, so there is nothing to gross up.
The issue only arises when the residue, or the relevant share of it, is exempt because it goes to a spouse, a civil partner, or to charity. In that situation, paying tax straight out of the residue would mean the exempt beneficiary is effectively funding a tax bill that belongs to somebody else's gift. HMRC's calculation stops that from happening by increasing the notional value of the chargeable legacy itself, so the correct amount of tax is charged on the estate as a whole rather than simply being netted off the exempt share.
A Worked Example
Take an estate worth £900,000 net of debts, where the available nil rate band has already been used against lifetime gifts, so none remains for the death estate. The will leaves £120,000 "free of tax" to a former business partner (a chargeable beneficiary) and the residue to a registered charity (an exempt beneficiary).
Without grossing up, you might expect HMRC simply to charge 40% on the £120,000 legacy, taking £48,000 from the residue and leaving the charity with £732,000. That is not how it works. Because the legacy is free of tax and the residue is exempt, the £120,000 has to be grossed up so that after notional tax at 40% is applied, the beneficiary still receives exactly £120,000.
The grossed-up figure is £120,000 divided by 0.60 (that is, 1 minus the 40% rate), which comes to £200,000. Tax at 40% on £200,000 is £80,000, and £200,000 minus £80,000 leaves £120,000, which is what the former business partner is entitled to. The estate's tax bill on this legacy has risen from a naively expected £48,000 to £80,000, a difference of £32,000, purely because of how the gift was drafted. The charity's share of residue falls correspondingly, from £852,000 (900,000 minus the £48,000 naive figure) down to £700,000 (900,000 minus the legacy's true cost of £200,000).
The same £120,000 reaches the friend either way. What changes is how much extra tax the estate pays to get it there, and how much the charity loses as a result. If the testator's real intention was to be generous to the friend without eating into the charity's gift, this clause achieves the opposite.
One-Stage and Multi-Stage Grossing Up
Simple estates with a single free-of-tax gift and a wholly exempt residue can usually be grossed up in one calculation, as in the example above. Real wills are rarely that tidy. Where some legacies are free of tax and others are not, or where all legacies are free of tax but the residue is only partly exempt (split, say, between a spouse and adult children), HMRC's own methodology moves to what it calls four-stage grossing up. The statutory basis for attributing value to specific gifts for this purpose sits in section 38 of the Inheritance Tax Act 1984, which sets out how the value transferred by an estate is apportioned between specific gifts and gifts of residue when the transfer is not wholly exempt.
There are two further complications worth flagging early rather than discovering at IHT400 stage. The first is successive charges relief, also known as quick succession relief, which applies where the estate includes assets that already bore IHT on an earlier death within the preceding five years. The second is "Benham grossing," a term drawn from the 1995 case of Re Benham's Will Trusts, which concerns wills that give specific instructions about how residue should be divided between chargeable and exempt beneficiaries in a way that affects how the tax burden falls. HMRC's own online calculator does not cover either situation. Where they apply, HMRC asks executors to request the calculation directly through the IHT400 process rather than attempting it independently, and it is generally worth doing so rather than guessing, because a wrong assumption at this stage tends to surface later as an underpayment with interest attached.
Grossing Up and Inheritance Tax: Key Estate Planning Facts
Tax Concept or Fact | Impact on the Estate or Beneficiary |
Gifts 'Free of Tax' (Grossing Up) | When a specific gift is left 'free of tax', the Inheritance Tax (IHT) due is paid by the residuary estate. This effectively increases the gift's value for tax purposes because the tax paid is itself treated as a further taxable gift (grossing up), which can push the estate into higher tax brackets and deplete the residue. |
Simple vs. Double Grossing Up | Simple grossing up applies when the residue is wholly taxable. Double (or multi-stage) grossing up is required when the residue is partially exempt (e.g., shared with a charity) and partially taxable; this creates a complex circular calculation where tax reduces the exemption, further increasing the total IHT burden. |
Charitable Exemptions and Gifting | While gifts to charity are exempt, leaving 'free of tax' gifts alongside a charitable residue can diminish the intended charitable benefit. The grossed-up tax on specific gifts must be deducted before the charity receives its portion, reducing the actual value of the charitable relief and increasing the estate's effective tax rate. |
10% Rule for Reduced IHT Rate | Leaving at least 10% of the net estate to a qualified charity can reduce the overall IHT rate from 40% to 36%. However, grossing up artificially inflates the chargeable estate value, which can push the estate above the baseline amount, potentially causing the charitable gift to fall below the 10% threshold and losing the lower tax rate. |
Legal Defaults and Directives | Under IHTA 1984 S.211, specific gifts default to being 'free of tax' if the Will is silent, shifting the burden to the residue. Technical approaches like Re Ratcliffe (division before tax) or Re Benham (division after tax) determine how tax is apportioned, with the Benham method typically resulting in much higher overall IHT liabilities. |
The 36% Reduced Rate and Charitable Gifts
Grossing up interacts with the reduced 36% rate of IHT in a way that trips up even experienced drafters. Where at least 10% of a net estate passes to charity, the whole of the chargeable estate is taxed at 36% instead of 40%. If a free-of-tax legacy to a non-exempt beneficiary sits alongside a charitable residue that is being tested against, or is intended to meet, that 10% threshold, the grossing up calculation has to be run using the correct rate, and the order of operations matters. Increasing the grossed-up value of a chargeable legacy reduces the residue passing to charity, which can in turn reduce the charitable share below the 10% threshold needed for the reduced rate to apply at all. A gift that was drafted to be generous to a friend can, in a poorly modelled will, end up disqualifying the estate from the reduced rate altogether, costing the charity considerably more than the legacy itself.
This is not a theoretical risk. Where a testator's stated intention is to leave "at least 10% to charity," the drafting needs to build in enough headroom to survive a free-of-tax legacy's grossing up effect, or the clause needs to be built the other way round, calculating the charitable share after the grossed-up cost of other gifts rather than before it.
Common Drafting Mistakes That Trigger This Unintentionally
● Leaving a fixed "tax-free" pecuniary legacy to a friend, godchild, or unmarried partner where the residue passes to a spouse or to charity, without modelling the grossing up cost at the time the will is made.
● Assuming that "free of tax" only affects the named beneficiary's own tax position, when in fact it reshapes the tax calculation for the whole estate.
● Failing to review an old will after a change in marital status. A will drafted when residue passed to adult children, later updated so residue passes to a new spouse, can turn a previously harmless free-of-tax legacy into a grossing up problem overnight.
● Charitable giving clauses that target "10% of the net estate" without accounting for how grossing up on other legacies reduces the base the 10% is measured against.
● Overlooking Business Relief and Agricultural Relief interactions, where specific gifts of relieved property sit alongside free-of-tax cash legacies. The relief has to be applied before grossing up is calculated, and getting the sequencing wrong produces the wrong tax figure.
Does Scotland or Wales Change the Position?
Inheritance Tax is a reserved matter, so the rates, thresholds and grossing up mechanics described here apply identically in England, Scotland, Wales and Northern Ireland. There is no separate Scottish or Welsh IHT regime, and GOV.UK's Inheritance Tax overview sets out the same 40% standard rate and 36% reduced rate across the whole of the UK.
What differs is the succession law surrounding the will, which can affect how a free-of-tax legacy interacts with the rest of the estate. In Scotland, legal rights allow a surviving spouse, civil partner, or children to claim a fixed share of a deceased person's moveable estate regardless of what the will says, and those claims are worked out before the residue is finalised. Where legal rights are claimed against an estate that also contains free-of-tax legacies, the grossing up calculation needs to reflect the reduced residue available once the legal rights claim has been satisfied, which is a step that is easy to miss if the will was drafted, or last reviewed, by someone unfamiliar with Scottish succession practice. In Wales, succession law follows the same principles as England, and GOV.UK's core guidance on how Inheritance Tax works is published in Welsh as well as English, but the underlying calculation is the same UK-wide test.
This interactive widget explains why leaving a “tax-free” legacy in a UK will can actually increase the Inheritance Tax bill on an estate, particularly when the residue passes to a spouse, civil partner or charity. It walks you through the HMRC grossing-up rules, shows a clear worked example, and includes a simple calculator so you can see the real cost of a free-of-tax gift on current 2026/27 figures. Use the tabs at the top to explore each topic, enter your own numbers in the calculator, and note the practical drafting tips to avoid costly surprises. Always treat the figures as educational guidance and seek professional advice before finalising a will.
Practical Steps Before Signing a Will
Anyone drafting or reviewing a will that contains a "free of tax" gift alongside an exempt residue should ask their adviser to run the grossing up calculation on the current estate value before the will is signed, not after death. HMRC's own grossing up calculator is a reasonable starting point for straightforward, single-stage cases, though it explicitly does not handle successive charges relief or Benham grossing, and it will not catch a business relief or reduced rate interaction on its own. For anything beyond a single free-of-tax legacy against a fully exempt residue, get the four-stage calculation checked by someone who does this regularly. The cost of getting it wrong is not a filing error. It is a smaller charitable gift, a smaller spousal inheritance, or a larger tax bill than the testator ever intended, discovered only once probate is already underway.
Key Takeaways
● A "free of tax" legacy protects the named beneficiary from IHT, but only by shifting that tax onto the rest of the estate.
● Grossing up applies only where a chargeable beneficiary has a tax-free gift and the residue, or part of it, is exempt (typically a spouse, civil partner, or charity).
● The grossed-up value of a legacy, not its face value, is what actually gets taxed, and the difference can run into tens of thousands of pounds on a moderate estate.
● Charitable giving clauses aimed at the 36% reduced rate threshold need to account for grossing up on other gifts, or they can fail to meet the 10% test.
● The nil rate band remains £325,000 and the residence nil rate band £175,000 for 2026/27, both frozen until April 2031 according to the Office for Budget Responsibility's analysis of Inheritance Tax, so more estates than in previous years will find themselves working through this calculation.
● Scotland's legal rights regime and Wales's shared succession law with England do not change the tax mechanics, but they can change the residue available once other claims are settled.
FAQs
Does leaving a legacy "free of tax" mean less Inheritance Tax is paid overall?
No. It does not reduce the total tax due on the estate and can increase it. It only changes who bears the cost, shifting it from the named beneficiary onto the residue, and where the residue is exempt, HMRC's grossing up rules can increase the total tax charged.
Who actually pays for the tax on a tax-free legacy?
The residuary beneficiaries pay it, through a reduction in what is left in the residue after the legacy and its associated tax have been deducted.
Does grossing up apply if the whole estate passes to my children?
Generally not, provided none of the residue is exempt. If everyone inheriting is a chargeable beneficiary, the tax on a free-of-tax gift is simply deducted from the residue without the need for a grossing up calculation.
Can I use HMRC's online calculator myself as an executor?
You can, for straightforward cases involving a single stage of grossing up. HMRC advises against using it where successive charges relief or Benham grossing applies, or where the estate includes relieved business or agricultural property, and asks executors to request the calculation directly when completing the IHT400 account.
How does grossing up affect a charity's 10% share for the reduced 36% rate?
It can reduce it. If grossing up increases the effective cost of a free-of-tax legacy, less passes to charity through the residue, which can push the charitable share below the 10% threshold needed for the reduced rate, increasing the overall tax rate on top of the reduced amount reaching the charity.
Is the position different for a Scottish will?
The tax rules are identical UK-wide. What can differ is the residue actually available for grossing up, because Scottish legal rights claims by a spouse or children are settled before the residue is finalised, which can change the figures the calculation starts from.
Should I avoid "free of tax" wording in my will altogether?
Not necessarily. It is a legitimate and sometimes useful drafting tool, particularly where a testator wants certainty for a specific beneficiary regardless of how the rest of the estate performs. The point is to have the grossing up cost modelled at the time the will is drafted, so the testator understands the true cost to the residue before signing.
Does grossing up apply to lifetime gifts as well as legacies in a will?
The same underlying principle, protecting a recipient from bearing tax that is instead charged elsewhere, can arise with certain lifetime chargeable transfers where the donor agrees to bear the tax, but the mechanics discussed in this article relate specifically to gifts made under a will and the interaction with an exempt residue.
What happens if the residue turns out to be insufficient to cover the grossed-up tax?
The legacies are abated, meaning they are reduced proportionately, in the order set out in the will or, failing that, under the general rules of administration. This is another reason to have the figures checked while a will can still be amended, rather than leaving it to be discovered during administration.
Does grossing up change if the estate includes property that qualifies for Business Relief or Agricultural Relief?
Yes. Relieved property has to be taken out of the calculation, or its value reduced by the applicable relief, before the grossing up exercise is run on the remaining chargeable gifts and residue. Running the calculation in the wrong order produces the wrong result.
About the Author:
Adil Akhtar, ACMA, CGMA, FCMA (membership ID is 990250923) serves as CEO and Chief Accountant at Pro Tax Accountant, bringing over 18 years of expertise in tackling intricate tax issues. As a respected tax blog writer, Adil has spent more than eighteen years delivering clear, practical advice to UK taxpayers. He also leads Advantax Accountants (registered with Companies House), combining technical expertise with a passion for simplifying complex financial concepts, establishing himself as a trusted voice in tax education.
Email: adilacma@icloud.com
Disclaimer: This article sets out the general position under UK tax law for the 2026/27 tax year. The information has been checked against HMRC guidance and other official sources at the date shown above, and is reviewed when the rules change. Tax legislation is complex and outcomes depend on your individual circumstances, so this article is provided for general information and does not constitute advice on which you should act. Any figures or worked examples are illustrative. Before making any decision, obtain advice specific to your situation from a qualified professional. Pro Tax Accountant accepts no liability for loss arising from reliance on this article alone.
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