Do You Need to File IHT400? Who Files, Schedules & Deadlines

IHT205 vs IHT400: What Changed?

Before 2022, many estates used the shorter IHT205 return (for excepted estates with simpler circumstances). Following a recommendation from the Office of Tax Simplification, HMRC abolished IHT205 for deaths on or after 1 January 2022. The excepted estate rules were updated and extended instead, so more estates fall outside the need for any IHT account at all, while those that do file must use IHT400.

The key change: estates that previously used IHT205 but were not truly "excepted" must now file IHT400 instead.

Do You Need to File IHT400? Excepted Estates Explained

You do not need to file IHT400 if the estate qualifies as an "excepted estate." Since January 2022, the excepted estate rules are:

Being under one of those limits is necessary but not sufficient. GOV.UK lists circumstances that force full details even where no tax is due — among them where the person gave away over £250,000 in the seven years before death, gave gifts they continued to benefit from, left an estate worth more than £3 million, had foreign assets worth more than £100,000, or held assets worth over £250,000 in trust or held more than one trust. Check that list before concluding an estate is excepted.

If the estate does qualify as excepted, you report its estimated value on the probate application instead of filing IHT400. No IHT account is needed — and if you do not need probate at all, you do not need to report the value of an excepted estate at all.

IHT400: The Main Form

IHT400 is a 19-page main form covering:

• Details of the deceased and the person filing (the "liable person").
• Summary of all assets at the date of death.
• Summary of all liabilities (debts, mortgages, expenses).
• Gifts made in the 7 years before death.
• Trusts and settled property.
• Exemptions and reliefs being claimed (e.g. spouse exemption, BPR, RNRB).
• IHT calculation — tax payable and instalments if applicable.

The main form directs you to complete relevant supplementary schedules for different asset types. You only complete the schedules applicable to your estate.

Key IHT400 Supplementary Schedules

Deadline and Payment

There are two different deadlines, and they are the thing this subject is most often got wrong on.

• The form: IHT400 must be submitted within 12 months of the death, and before applying for probate. GOV.UK: “If the estate owes Inheritance Tax, you must report its value within one year using form IHT400.” A financial penalty can follow if you miss it without a reasonable excuse.
• The tax: payable by the end of the sixth month after the month of death — GOV.UK’s own example is that someone who died in January must be paid for by 31 July. Interest runs from that date, not from the date of death.

So the tax falls due roughly six months before the account does, which is why executors so often find themselves paying before they have finished valuing. For more on the cost of delays, see our guide to probate delays and IHT interest.

A common challenge is that you must pay IHT before you can obtain probate — but you cannot access estate funds to pay it without probate. The solution is the Direct Payment Scheme, which allows HMRC to collect IHT directly from the deceased's bank accounts. See our guide to paying IHT before probate.

Inheritance tax on assets that take time to sell — land and buildings, controlling shareholdings, certain unlisted shares, a business run for profit — can be paid in ten equal annual instalments. You have to say on the IHT400 that you want to do this. The first instalment is due at the end of the sixth month after the death and the rest fall on that date each year; you pay no interest on the first instalment unless it is late. One recent change: for assets inherited from 6 April 2026 onwards, instalments are interest-free where the asset qualifies for Agricultural Relief or Business Relief.

The IHT Reference Number

Before submitting IHT400, you must obtain an inheritance tax reference number from HMRC — GOV.UK says to get it at least three weeks before you make a payment. Apply on HMRC’s online service (this replaced the paper IHT422); trusts use form IHT122 instead.

What HMRC sends back afterwards depends on where you are, and this is one of the most commonly out-of-date things written about probate. Since 18 January 2024:

• England and Wales: there is no IHT421 any more. HMRC “will send you a unique code so you can apply for probate online”, together with the probate figures.
• Scotland: confirmation, not probate. You send form C1 with the IHT400 and HMRC stamps and returns it.
• Northern Ireland: IHT421 survives, and only here. The form is now published as “Inheritance Tax probate summary for Northern Ireland (IHT421)” and HMRC stamps and returns it.

Common Mistakes in IHT400

• Failing to include all assets — check pension death benefits (if paid to estate), life insurance not written in trust, and foreign assets.
• Using insurance values for jewellery instead of open market values — see our guide to valuing jewellery and art.
• Missing gifts made in the 7 years before death — these must be reported in Schedule IHT403.
• Failing to claim all available reliefs — particularly the transferable nil-rate band (IHT402) and RNRB (IHT435/IHT436).
• Trying to deduct administration costs. Funeral expenses (box 81) and the deceased’s own debts (boxes 80 and 82) reduce the taxable estate; the costs of dealing with the estate afterwards do not. The IHT400 notes are explicit: “probate fees, any solicitor’s or estate agent’s fees and any valuation fees incurred in dealing with the deceased’s estate cannot be deducted.”

For the full IHT calculation and reliefs available, see our inheritance tax guide for 2026–27. For probate application after IHT400 is submitted, see our guide to PA1P vs PA1A probate application forms.

Related Guides

• Paying IHT Before Probate
• Valuing a Property for Probate
• Transferring the Nil Rate Band Between Spouses
• Executor First Steps
• Complete UK Probate Guide 2026