IHT400 Form UK: A Complete Guide to the Inheritance Tax Account

Updated: 20 May 2026 • Reading time: 9 min

The IHT400 — formally known as the Inheritance Tax Account — is the full HMRC form that personal representatives (executors and administrators) must complete when inheritance tax is payable or the estate is outside the simplified “excepted estate” rules. It is the most detailed and consequential document in the estate administration process, and errors can lead to HMRC enquiries, interest charges, and penalties. This guide explains when the IHT400 is needed, which supplementary schedules apply, how to value the estate, the payment rules, and what to expect if HMRC opens an enquiry.

When Is the IHT400 Required?

Since 1 January 2022, many estates no longer need to file any IHT form with HMRC. The simplified excepted estate process covers estates where:

• The estate is below the IHT threshold (£325,000 nil-rate band, plus any transferred nil-rate band from a deceased spouse or civil partner), and
• The gross value of the estate does not exceed £3m (for deaths on or after 1 January 2022), and
• The estate does not include a trust in which the deceased had a beneficial interest, and
• The deceased did not make chargeable lifetime transfers or gifts with reservation of benefit, and
• The deceased was domiciled in England and Wales at the time of death.

Where the estate falls outside these rules — because IHT is payable, the estate is above £3m, there is a trust interest, substantial lifetime gifts were made, or the deceased had foreign domicile — the full IHT400 must be submitted.

Structure of the IHT400

The IHT400 itself is the main return — approximately 12 pages — covering the deceased’s estate at death: assets in the UK, jointly owned assets, foreign assets, nominated assets, and assets in trust. The form then asks about deductions (debts, funeral expenses, liabilities) and calculates the net estate value.

The main form alone is rarely sufficient. Most estates that require an IHT400 also need one or more supplementary schedules (IHT4xx series):

• IHT401 — Domicile outside the United Kingdom (foreign domicile estates)
• IHT402 — Claim to transfer unused nil-rate band (where a deceased surviving spouse or civil partner wishes to claim the transferred nil-rate band from their pre-deceased partner)
• IHT403 — Gifts and other transfers of value (lifetime gifts in the 7 years before death, gifts with reservation of benefit)
• IHT404 — Jointly owned assets (property and bank accounts held in joint names)
• IHT405 — Houses, land, buildings and interests in land
• IHT406 — Bank and building society accounts
• IHT407 — Household and personal goods
• IHT408 — Household and personal goods donated to charity
• IHT409 — Pensions (death benefits and pension rights)
• IHT410 — Life assurance and annuities
• IHT411 — Listed stocks and shares
• IHT412 — Unlisted stocks, shares and investments
• IHT413 — Business or partnership interests and assets (for Business Property Relief claims)
• IHT414 — Agricultural Relief (for agricultural land, farm buildings, and farm cottages)
• IHT415 — Interest in another estate (where the deceased was also a beneficiary of an estate not yet fully administered)
• IHT416 — Debts owed to the estate
• IHT417 — Foreign assets
• IHT418 — Assets held in trust
• IHT419 — Debts owed by the deceased
• IHT420 — National heritage assets (conditionally exempt property)
• IHT421 — Probate summary (the receipt sent to HMCTS confirming IHT position — not completed by the applicant but issued by HMRC)
• IHT423 — Direct Payment Scheme — authorisation for a bank to pay IHT directly to HMRC before probate

In a typical straightforward taxable estate with one property, bank accounts, and some investments, the personal representative would expect to complete: IHT400, IHT405, IHT406, IHT411, IHT402 (if a transferred nil-rate band is claimed), and IHT423 (for the Direct Payment Scheme).

Valuing the Estate for IHT Purposes

All assets must be valued at their open market value on the date of death — the price a willing buyer would pay a willing seller in an arm’s length transaction. Key rules:

• Residential property: Use a RICS-qualified surveyor for a formal Red Book valuation. HMRC’s Valuation Office Agency (VOA) reviews property valuations on IHT400s and will challenge low valuations. Comparables from Zoopla or Rightmove are not sufficient on their own — use them to check plausibility, not as the primary evidence.
• Quoted shares and investments: Use the “quarter-up” rule — the lower of (a) the mid-market price quoted on the death date, and (b) the lower quoted price plus one-quarter of the difference between the lower and higher quoted prices. Most share registrars will provide a death certificate valuation on request.
• Business interests: Require specialist valuation, particularly for unquoted company shares. An accountant or business valuer familiar with IHT is essential. HMRC will scrutinise Business Property Relief claims carefully.
• Personal possessions: Professional valuation for jewellery, art, or collections above a modest value. For ordinary household goods, a reasonable estimate is acceptable, but HMRC may query unusually low figures.
• Foreign assets: Convert to sterling using the Bank of England exchange rate on the date of death. Use IHT417 for foreign assets.

Payment Deadlines and the Direct Payment Scheme

IHT on most assets must be paid by the end of the sixth month after the month of death. For example, a death on 10 April 2025 means IHT must be paid by 31 October 2025. After this date, HMRC charges interest at the current statutory rate (which has been around 7–8% in recent years).

The catch-22 is that executors cannot access the deceased’s bank accounts without a grant of probate, but probate cannot be obtained without paying IHT first. The solution is the Direct Payment Scheme (DPS):

• Most major banks and building societies participate in the DPS.
• Executors complete form IHT423 for each institution and send it directly to the bank (not to HMRC).
• The bank pays HMRC directly from the deceased’s accounts without requiring the grant of probate.
• Separate IHT423s must be submitted to each institution — there is no single aggregated form.
• Processing typically takes 2–4 weeks from the bank receiving the IHT423.

Alternatively, executors can pay IHT from their own funds and be reimbursed from the estate once probate is granted. Check whether the estate has sufficient accessible funds — e.g. Premium Bonds can be cashed before probate by NS&I, and some institutions allow small withdrawals on production of the death certificate.

Instalment Option for Certain Assets

For “instalment option property”, executors can elect to pay IHT in ten equal annual instalments (the first due at the normal 6-month deadline). Instalment option property includes:

• Land and buildings (including the family home)
• A business or share in a partnership
• Unquoted shares where certain conditions are met
• Quoted shares that gave the deceased control of the company

Interest accrues on the outstanding instalments for land, except where Business Property Relief or Agricultural Property Relief applies, in which case the instalments are interest-free. The election is made in the IHT400; the executor must continue to pay annual instalments on time or interest will be charged on arrears. The full outstanding balance becomes immediately payable if the property is sold.

Submitting the IHT400 and the IHT421 Link to Probate

The completed IHT400 and all applicable supplementary schedules are sent to HMRC’s Inheritance Tax office in Nottingham (address on the form). HMRC reviews the account and — once IHT has been paid or appropriate arrangements made — issues the IHT421 (Probate Summary). Since 2021, for online probate applications, HMRC sends the IHT421 electronically to HMCTS, and the personal representative simply enters the IHT421 reference number in the online probate application.

HMRC’s processing times for IHT400s vary. In 2025–2026, HMRC has been running at 6–10 weeks from receipt of the complete account. Complex accounts with disputed valuations or BPR/APR claims take longer. Submit early — the 6-month IHT payment deadline is hard, but HMRC will process the account and issue the IHT421 separately from the payment timeline. Pay IHT by the deadline even if the IHT421 has not yet been issued.

HMRC Enquiries and the Certificate of Discharge

HMRC may open a formal enquiry into the IHT400. Common triggers include:

• Property valuations that appear significantly below market value
• Business Property Relief claims on assets where HMRC questions whether BPR applies (e.g. investment-heavy businesses)
• Agricultural Property Relief claims on farmhouses or land not actively farmed
• Large gifts in the 7 years before death with limited documentation
• Reservation of benefit issues (e.g. gift of the family home where the deceased continued living there)

An enquiry is not an accusation — it is HMRC’s formal process for checking the account. Respond promptly with evidence (valuations, bank statements, gift records). Professional representation significantly improves outcomes in contested valuations and BPR/APR disputes.

Once the estate is fully administered and all IHT paid, the executors can apply for a Certificate of Discharge (form IHT30). Once issued, HMRC cannot pursue further IHT from the executors personally — though it retains the right to recover from beneficiaries in certain circumstances. The certificate is good practice for estates where HMRC scrutiny is likely.

Frequently Asked Questions