This guide explains how to complete the IHT400 form, the information to gather, the schedules that may apply and the difference between reporting the estate and paying any tax due. It is UK general information, not legal or tax advice. HMRC updates forms and rules, so always check the latest IHT400 form and notes on GOV.UK before sending anything.

In this guide:

• What IHT400 is and when it is generally required
• What to prepare before completing the account
• How the main account and supplementary schedules fit together
• Deadlines, payment, the IHT reference and submission
• Common mistakes, practical help and IHT400 FAQs

What is the IHT400 form?

IHT400 is the detailed Inheritance Tax account used by personal representatives. It records the deceased's assets, liabilities, gifts, reliefs and exemptions. The account is made up of the main 19-page IHT400 form and only the supplementary schedules relevant to the estate.

Who needs to complete an IHT400?

The personal representatives (usually executors named in the will, or administrators where there is no will) are responsible for the account. They can complete it themselves or appoint a solicitor, accountant or other authorised agent to help.

HMRC says to use IHT400 where there is Inheritance Tax to pay, or where there is no tax to pay but the estate does not qualify as an excepted estate. The exact rules for excepted estates and reduced reporting depend on the facts of the estate and the date of death. Do not use the nil-rate band alone as a shortcut for deciding which form is needed.

If you are unsure, start with HMRC's current IHT400 notes, our inheritance tax forms guide and the inheritance tax calculator. A calculator can help you explore the figures, but it cannot determine whether an estate is excepted.

When might you not need an IHT400?

An estate may not need a full IHT400 if it qualifies as an excepted estate. This is a separate HMRC test; it is not just a question of whether the estate is below a particular allowance or whether the deceased was married. Review the current notes and probate application requirements carefully, particularly where there are lifetime gifts, trusts, overseas assets, a previous spouse or civil partner, or unusual asset ownership.

What do you need before completing IHT400?

Make a working list before you start. HMRC asks personal representatives to make full enquiries and be able to support the figures and statements in the account.

• Personal and probate documents: death certificate, will and codicils, executor details, date of birth, marital or civil-partnership history and National Insurance number where available.
• Assets: bank and building society balances at the date of death, investments, pensions, insurance, property and land, business interests, vehicles and personal belongings.
• Liabilities: mortgages, loans, credit cards, unpaid bills and other enforceable debts. Keep evidence rather than relying on estimates.
• Gifts and transfers: records of gifts, transfers for less than market value, trusts and other relevant transactions during life.
• Evidence of reliefs or exemptions: for example, documents supporting spouse/civil-partner exemption, charitable gifts, a transferred nil-rate band, residence nil-rate band, Agricultural Relief or Business Relief.

For property and land, use an accurate date-of-death valuation. HMRC says this can be obtained from an estate agent or chartered surveyor; a professional valuation is not automatically a legal requirement in every case, but a specialist valuation may be sensible for unusual, high-value or difficult-to-value property. Our estate inventory builder can help organise the initial list of assets and debts.

How to complete the IHT400: a practical sequence

Do not rely on page numbers in older guides. HMRC updates the account and its notes. Work through the current form in its own order and use the questions in the main account to identify the schedules you need.

1. Read the current IHT400 notes first. Confirm whether the full account is required and identify any time-sensitive claims or payment arrangements.
2. Complete the identifying and estate-administration details. Use names and dates that match official documents, and take care with domicile or long-term UK residence questions.
3. Prepare the relevant schedules before finalising totals. The main form directs you to schedules for assets, liabilities, gifts, reliefs and exemptions.
4. Check every valuation and debt at the date of death. Include only figures you can explain and support.
5. Carry schedule totals into the account and complete the calculation. Recheck that reliefs, exemptions and claims are supported by the correct schedule or evidence.
6. Make copies and send only the material HMRC asks for. The current form says not to send original documents unless HMRC asks for them.

How is Inheritance Tax calculated on IHT400?

There is no universal one-line formula. The account brings together the gross estate, allowable liabilities, relevant lifetime transfers, exemptions, reliefs and available allowances. The result can be affected by the nil-rate band, a transferable nil-rate band, the residence nil-rate band, spouse or civil-partner exemption, charitable gifts, Agricultural Relief, Business Relief and other rules.

The standard IHT rate is generally 40% on the taxable part of an estate. A reduced 36% rate can apply in some circumstances where a qualifying charitable legacy meets HMRC's test; it is not enough to assume that any gift to charity reduces the rate. Use the current HMRC calculation and notes, and get advice where the figures are material or the estate is complex.

IHT400 schedules explained

Complete only the schedules the main IHT400 directs you to complete. The schedule number matters: an older guide, checklist or downloaded form can be out of date. The table below reflects the core current schedules; use HMRC's links and notes to confirm the version for the date of death.

There are further IHT schedules and claims for particular situations, including heritage assets, probate in Northern Ireland, an IHT reference, direct payment arrangements and residence nil-rate band claims. Use our forms directory and the latest HMRC notes rather than assuming this list covers every possible estate.

Property, goods and joint assets

Use IHT405 for property and land, not IHT401. It asks for houses, land, buildings and interests in land. IHT404 deals with jointly owned assets, while IHT407 is for household and personal goods. Value assets accurately at the date of death and keep the evidence used. Do not rely on arbitrary thresholds for jewellery, art, antiques or household contents: where an item is material or difficult to value, a specialist or auctioneer valuation may be appropriate.

For the current official forms, see IHT404, IHT405 and IHT407.

Gifts, exemptions and taper relief

IHT403 is for gifts and other transfers of value, not simply “all gifts over £250”. Gather a full record first, then consider whether an exemption or exclusion applies under the current rules. These can include the £250 small-gift exemption, the £3,000 annual exemption, normal expenditure out of income and wedding or civil-partnership gift exemptions. The conditions and interaction between exemptions matter, so do not omit a gift merely because of its size.

Taper relief does not reduce the value of a gift. It can reduce the IHT payable on certain chargeable lifetime transfers when the transfer was made more than three years before death and tax is due. It is not an automatic lower tax rate for every gift made between three and seven years before death. See our guide to the seven-year gift rule and HMRC's current IHT403 guidance.

IHT400 deadlines, payment and submission

There are two different timings to understand. HMRC's current IHT400 says the account must be sent within 12 months of the date of death. It also says interest is payable after six months. In practice, tax due usually needs to be dealt with before a grant can be issued, but that does not mean you must simply pay all IHT before you are allowed to submit the IHT400.

• IHT400 reporting: send the completed account and relevant schedules to HMRC within 12 months of the death.
• Payment and interest: IHT is generally due six months after the end of the month in which the person died. Interest can run on unpaid tax after that point.
• IHT reference: if there is tax to pay, apply for an IHT reference before sending IHT400. HMRC says to apply at least three weeks before you plan to send the account. You can apply through GOV.UK's Inheritance Tax payment service or, where appropriate, with IHT422.
• Payment options: there are different methods, including HMRC's Direct Payment Scheme for qualifying bank, building society and NS&I accounts. Instalments may be available for qualifying assets, such as some property or business interests.

Can IHT400 be completed online?

The current IHT400 is an interactive PDF, not an ordinary online submission form. HMRC says it can be completed on screen using Adobe Reader, then printed and sent following the instructions in the form and notes. Check the current form for the right address and accompanying documents; do not copy a postal address from an old article. You should normally send copies rather than original documents unless HMRC asks for originals.

What happens after you submit IHT400?

HMRC may review the account, calculations, valuations and supporting evidence. It can ask for further information or clarification. How long this takes depends on the estate and HMRC's workload, so avoid relying on fixed processing-time claims from older guides.

If you later find an error or a new asset or liability, act promptly and use the route HMRC specifies for correcting an account. Keep copies of what you sent and respond by any deadline in HMRC's correspondence. The IHT process and the probate application are related but separate; see our probate process timeline for a broader overview.

Common IHT400 mistakes to avoid

How long does IHT400 take to complete?

There is no reliable fixed number of hours. The time depends mainly on how quickly you can gather full date-of-death values, determine which schedules apply and resolve any questions about gifts, jointly owned assets, trusts, businesses, farms, foreign property or reliefs. Start the evidence-gathering early and work through the current HMRC notes methodically rather than rushing the account.

Can I complete IHT400 myself?

Some personal representatives complete a straightforward account themselves. That can be realistic where the estate is easy to value, the records are complete and there are no uncertain claims or complicated transactions.

Professional help can be particularly valuable where there are trusts, business or agricultural property, overseas assets, complex lifetime gifts, uncertain valuations, a blended family, a disputed will, a claim for relief or a significant potential tax consequence. This is about complexity and confidence, not an arbitrary estate-value threshold.

Helpful IHT400 resources

Official HMRC guidance

• Current IHT400 form, notes and calculation documents
• IHT403: gifts and other transfers of value
• IHT409: pensions, IHT417: foreign assets, IHT418: trust assets and IHT419: debts owed by the deceased
• HMRC's Agricultural Relief guidance

Inheritance Planner tools and guides

• Inheritance tax calculator
• Inheritance Tax calculator guide
• IHT forms guide and forms directory
• Nil-rate band and residence nil-rate band explained
• Seven-year gift rule, estate inventory and 2026 IHT reforms