How to fill in form IHT400
A plain-English walkthrough of HMRC's full inheritance tax account — which estates have to file it, the 16 main sections, the 21 supplementary schedules, the deadlines, and the unique code that connects it to probate. England & Wales.
This is the same official IHT400 file HM Revenue & Customs publishes on GOV.UK — the link below fetches the current version live from GOV.UK the moment you click it, so it can never go out of date.
Current version: August 2026 · confirmed on GOV.UK 23 August 2026
IHT400 is HMRC's full inheritance tax account. The form itself is long rather than hard; the real work is deciding which schedules apply and getting the two deadlines right — the tax is due before the form is.
Do you actually need IHT400?
Many estates never file IHT400 at all.
For deaths on or after 1 January 2022 the old short forms (IHT205 / IHT217) were abolished — an excepted estate now reports its values straight on the probate application and files no separate IHT form. The three pathways below tell you which route you are on before you start.
Estate clearly within the nil-rate band (£325,000 single, up to £1m for couples using both bands), with no foreign assets, no trusts, no large gifts and no business or agricultural relief claimed. The values go on the probate application (PA1P or PA1A); no IHT400.
Tax is due, OR the estate is over the threshold but reduced below it by exemptions, OR there are foreign assets, trusts, gifts above the NRB, or business/agricultural relief claims. This is the full account — and the walkthrough below.
Contested estates, complex trusts, mixed residence, large business succession, agricultural estates with operating tenancies. The form is the same; the analysis behind it is the work. This is not the place to do it yourself.
Two deadlines — and they're not the same date
The clock runs from the date of death.
The single most common mistake is treating the form deadline as the tax deadline. They are months apart, and the tax one comes first.
By the end of the sixth month after the month of death. Interest accrues on anything unpaid after that — at the published HMRC late-payment rate. This applies even if you can't pay in full; at minimum, pay what you can and start the instalment route for qualifying assets.
Within 12 months of the date of death, and before you apply for probate. Late delivery can attract penalties on top of interest. Most estates send the IHT400 well inside this window because probate can't proceed until HMRC has processed it.
Tax on land and buildings, a controlling shareholding, certain unlisted shares and a business can be paid in 10 equal yearly instalments. Interest generally applies to the balance. Tax on most other assets must be paid in full at the six-month mark.
Probate is not granted until HMRC has processed the IHT400 and issued the unique code you enter on the probate application. A delay in IHT400 processing is therefore a delay in probate.
How to fill in IHT400: the sixteen sections
The IHT400 runs linearly from identity, through assets, to the calculation.
Each section signals which schedules it triggers — that's the navigation work the decision matrix below makes tractable. The numbers come last.
Identity, date of birth, date of death, last address. Marital status.
Who HMRC writes to. Usually the lead executor; can be a solicitor or agent acting for the estate.
If a solicitor or accountant is the agent, this authorises HMRC to discuss the case with them.
Whether there's a will, dates of will and any codicils, name of solicitor (if any) holding it.
UK vs non-UK status. UK is default for UK-resident adults; a foreign element triggers IHT401.
Whether the deceased held assets abroad. If yes, IHT417 applies and may need IHT401 for status.
All sole-name accounts (joint accounts go on IHT404). IHT406 has the detailed schedule.
Listed shares (IHT411), unlisted shares (IHT412), government stocks, corporate bonds.
Houses, land, buildings owned. IHT405 schedule; valuations at date of death; mortgage outstanding.
Vehicles, valuables, art, jewellery, collectibles. IHT407 schedule.
All pension schemes the deceased held. IHT409 schedule. From April 2027, most unused funds are due to be included.
Life policies (IHT410); trust interests (IHT418). Trust policies are typically NOT in the estate.
Outstanding debts at death (IHT419). Deducted from the gross estate.
Reasonable funeral costs are deductible. Burial plot purchase counts; flowers, headstone and memorial typically count.
Where a spouse takes assets free of IHT; where charity takes assets free of IHT; gifts in the last 7 years (IHT403).
The calculation: gross estate − reliefs − exemptions − debts − charitable gifts × the applicable rate. The IHT Calculator on this site walks the maths.
Try a section now — plain English on every box
Every IHT400 box explained in plain English, with the source record that fills it in for members. Your answers save to this device only — no account, no signup. Section 1 is fully live; Sections 2–16 are in active build.
Deceased's details
The personal facts that anchor everything else. All of these come from the death certificate or the deceased's identity records (passport, driving licence).
Section 1 captures the deceased's name, date of death, NINO, occupation, marital status and, critically, the domicile/residence box that determines the territorial scope of the charge. The single biggest trap from deaths on or after 6 April 2025 is that the form no longer turns on common-law or deemed domicile: under FA 2025 the worldwide-versus-UK-only charge now depends on whether the deceased was a 'long-term UK resident' (broadly UK-resident in at least 10 of the previous 20 tax years), so old IHTA 1984 s.267 deemed-domicile reasoning and the '17 of 20 years' rule are obsolete. Getting this status wrong wrongly includes or excludes foreign assets and the whole account.
Which schedules do you need? Most estates need three or four
Twenty-one supplementary schedules exist; deciding which apply is where most executors get stuck.
Pick the situation that matches the estate — the relevant schedules appear with the trigger that brings each one in.
Joint property, joint accounts, joint investments — anything held in two or more names.
Sole-name bank accounts, savings, building society accounts. Always required if any exist.
Furniture, jewellery, art, collectibles. Even if modest — most estates list contents at a 'household effects' total.
Three ways to pay — each solves a different problem
The estate must find the tax before assets are released — but the assets that would pay it are usually frozen until probate.
These three routes are how that circular problem gets solved.
Instructs the deceased's bank or building society to pay the Inheritance Tax directly to HMRC, before probate. All the UK majors participate. The cleanest route for liquid estates — the money never passes through the executor's hands. Send the IHT423 to each institution alongside the IHT400.
The executor pays HMRC from their own funds, then reclaims from the estate after probate. Used where the estate is illiquid (mostly property) and the executor can fund the tax temporarily. It requires the executor to actually have the cash — the bill on an estate above the threshold is meaningful.
Tax on land and buildings, a controlling shareholding, certain unlisted shares and a business can be paid in 10 equal yearly instalments — useful where selling would force a fire sale. Interest is generally charged on the outstanding balance (with an interest-free carve-out from April 2026 for assets qualifying for Agricultural or Business Relief). Tax on most other assets cannot be paid this way.
IHT400 is the calculation.
The records are what make filling it in possible.
Bank statements, pension valuations, property valuations, gift letters, beneficiary nominations. Most of the hours a solicitor charges to complete IHT400 are the hunt for those documents — not the form itself.
Organised records collapse the hunt to days. The IHT Calculator works out the position before you reach Section 16.
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