IHT400

How to fill in IHT400: a step-by-step guide

Last checked 5 October 2026 against HMRC’s forms, guidance and the law · rules version 2026-10-05.1

To fill in an IHT400, HMRC's "Inheritance Tax account", first check that the estate is not an "excepted estate". Then answer boxes 1 to 48 to find which schedules you need, complete them, copy their totals into boxes 49 to 108 and work out the tax, or tick the box asking HMRC to do it. Everyone applying for the grant signs the declaration, and the account goes to Inheritance Tax, HM Revenue and Customs, BX9 1HT, within 12 months of the death; HMRC usually sends the code needed to apply for probate within 20 working days of receiving the account or the tax, whichever is later.

Step 1: Check that you need an IHT400

An IHT400 is needed when there is Inheritance Tax to pay, or when there is none but the estate is not an excepted estate (IHT400, page 1). For deaths on or after 1 January 2022, an estate is broadly excepted if its gross value, including the deceased's share of joint assets and gifts in the last 7 years, is no more than £325,000, the "nil rate band" taxed at 0% (£650,000 with a full transfer of a late spouse's nil rate band), or no more than £3,000,000 with everything above £325,000 going to a spouse, civil partner or charity (SI 2004/2543 reg. 4, as amended; IHTM06012, IHTM06013). The residence nil rate band (up to £175,000 more when a home goes to children or grandchildren) does not count.

The excepted estates guide sets out every condition, and the free check asks the questions in order. Where most of the estate goes to a spouse, civil partner or charity and no tax is due, the IHT400 Notes may allow a shorter "reduced" account.

Step 2: Get an Inheritance Tax reference number if tax is payable

If tax is payable, you need an Inheritance Tax reference number for box 3. Apply online through GOV.UK, or on paper with Schedule IHT422, at least 3 weeks before sending the IHT400; none is needed if there is no tax to pay.

Tax is due by the end of the sixth month after the month of death, with interest from the first day of the seventh month (IHTA 1984 ss.226 and 233), at 7.75% a year since 9 January 2026. See interest and late payment and paying before probate.

Step 3: Gather the papers and the values at the date of death

List the assets, debts and any gifts, and write to each bank, pension scheme, insurer and supplier for the figure at the date of death. Everything is valued at "open market value": what it would have sold for that day. Round assets down and debts up to the nearest pound (IHT400 Notes).

If a figure cannot be found after full enquiries, the law allows a provisional estimate, listed in the declaration and corrected later (IHTA 1984 s.216(3A)). HMRC's PDF cannot be saved part-filled, so have every figure ready first.

Step 4: Fill in boxes 1 to 28

Boxes 1 to 13a describe the deceased. Box 6b asks whether they were a long-term UK resident, meaning resident for at least 10 of the 20 tax years before the year of death (IHTA 1984 s.6A); if not, Schedule IHT401a is needed.

Boxes 14 and 15 ask for the National Insurance number and any Unique Taxpayer Reference, and boxes 21 to 23 for the bank account for any repayment. Boxes 16 to 20 cover any power of attorney and the contact person. Boxes 24 to 28 are about the will: enclose a copy, never the original, and list at box 28 anything it mentions that the deceased no longer owned.

Step 5: Choose and fill in the schedules (boxes 29 to 48)

Each question from 29 to 47 names a schedule. The common ones, with their IHT400 box:

IHT402 (29c): a late spouse's unused nil rate band
IHT403 (30): gifts in the 7 years before death
IHT404 (31): jointly owned assets
IHT405 (32): houses, land and buildings
IHT406 (33): bank and building society accounts and NS&I
IHT407 (34): household and personal goods
IHT409 (36): pensions
IHT410 (37): life assurance and annuities
IHT411 (38): listed stocks and shares
IHT416 (43): money owed to the deceased
IHT417 (44): foreign assets
IHT419 (46): some debts, such as family loans
IHT435 and IHT436 (29a, 29b): the residence nil rate band and its transfer
IHT430 (109): the 36% reduced rate when 10% or more of the net estate goes to charity
IHT423 (120): the Direct Payment Scheme

Fill in every schedule you need except IHT435 and IHT436 before going further; those two come after box 108 (IHT400, box 48).

Step 6: Copy the totals into boxes 49 to 79

Pages 7 and 8 have two columns. Column B is for property on which tax may be paid in 10 yearly instalments while unsold, mainly houses, land and buildings. Column A is for everything else, and its tax must be paid before the grant (IHT400 Notes; IHTA 1984 s.227).

So the home goes in box 51 and a share of a jointly owned house in box 49 (from IHT404 box 5), both in column B. Bank accounts (box 52, IHT406 box 1), household goods (box 55, IHT407 box 6), listed shares (box 63, IHT411 box 2) and other joint assets (box 50) go in column A. Box 79 is the gross estate in the UK. Foreign assets go on IHT417, not in boxes 49 to 96.

Step 7: Take off debts and exemptions, and add other assets (boxes 80 to 108)

Box 80 lists mortgages and loans secured on column B property, box 81 the funeral and headstone, and box 82 other debts such as bills and care fees. Boxes 83 to 91 take them off the right column, giving the net estate in box 91.

Boxes 92 and 93 hold exemptions on sole-name assets, such as spouse, civil partner or charity exemption. Exemptions on joint assets go on IHT404, and a transferred nil rate band never goes here. Boxes 97 to 107 add other assets, such as foreign assets. Box 108 is the total chargeable estate. Now fill in IHT435 and IHT436 if the residence nil rate band is claimed.

Step 8: Work out the tax, or ask HMRC to (boxes 109 to 120)

If you are filling in the form yourself without a solicitor or other adviser, HMRC will work out the tax if you tick the box under box 108. If there is no tax to pay, go straight to box 121.

Box 109: "Yes" if the 36% reduced rate applies, with Schedule IHT430.
Box 110: whether to pay the tax on unsold column B property in 10 yearly instalments, with interest. This is the executors' choice.
Boxes 111 to 119: the simple calculation, which can be used only if all the tax is paid by the end of the sixth month and not by instalments, lifetime gifts are below the nil rate band, and there is no double taxation relief, successive charges relief or 36% rate. Otherwise use the IHT400 Calculation form.
Box 120: the Direct Payment Scheme, through which banks, building societies and NS&I pay the tax from the deceased's sole-name accounts. Send one IHT423 per account to that organisation when the IHT400 goes to HMRC.

Step 9: Sign the declaration and use the checklist (boxes 121 and 122)

Box 121 asks which grant you will apply for: probate if there is a will, letters of administration if not. The declaration also asks you to list any boxes holding provisional estimates. Box 122 asks where the application is made and which schedules are enclosed.

Each person who will be named on the grant signs page 16, and HMRC returns forms where the declaration is not completed correctly (IHT400 Notes). The checklist on page 18 lists the copies to enclose, such as the will and valuations. Send copies, not originals.

Step 10: Send the account and wait for the probate code

Post everything to Inheritance Tax, HM Revenue and Customs, BX9 1HT. HMRC's form asks for it within 12 months of the date of death; the legal limit is 12 months from the end of the month of death (IHTA 1984 s.216(6)(a)). Send any cheque separately.

HMRC then sends a code confirming that enough tax has been paid, usually within 20 working days of receiving the IHT400 or the payment, whichever is later; page 17 lets you ask for it by e-mail. The executor needs this code to apply for probate.

After the grant, HMRC may ask questions, for example about valuations. If you have not heard from HMRC 14 weeks after sending the IHT400, no further checks will be carried out. If values change, for example when a provisional estimate becomes final, HMRC is told on a corrective account (form C4), once values are final or 18 months after the death, whichever is sooner.

Worked example: a widow's estate

A hypothetical widow died on 17 May 2026. Her husband died on 3 March 2015 and left his £400,000 estate to her, so none of his nil rate band was used; because he died before 6 April 2017, his residence nil rate band counts as fully unused. Her will leaves everything to her two children. She owned her house (£600,000), £500,000 in two bank accounts and household goods worth £10,000. The funeral and bills came to £6,000, and she made no gifts. The schedules are IHT402, IHT405, IHT406, IHT407, IHT435 and IHT436.

Box	What it shows	Amount
51	House (IHT405, column B)	£600,000
52	Bank accounts (IHT406 box 1)	£500,000
55	Household goods (IHT407 box 6)	£10,000
79	Gross estate in the UK	£1,110,000
108	Total chargeable estate (after £6,000 of debts; no exemptions)	£1,104,000
111	Residence nil rate band: £175,000 plus £175,000 transferred (IHT435 box 25)	£350,000
112	Box 108 minus box 111	£754,000
113	Gifts	£0
114	Value chargeable before the nil rate band	£754,000
115	Nil rate band	£325,000
116	Transferred nil rate band (IHT402 box 21)	£325,000
117	Total nil rate band	£650,000
118	Value chargeable to tax	£104,000
119	Inheritance Tax at 40%	£41,600

The tax is due by 30 November 2026, with interest from 1 December 2026. Here the executors decide to pay it all by then, so the simple calculation can be used. Had they chosen instalments on the house, they would use the IHT400 Calculation instead, which puts £22,609.60 of the tax on the house, payable over 10 years with interest.

The legal deadline for the IHT400 is 31 May 2027, and for the IHT402 and IHT436 claims 31 May 2028.

Working on an IHT400 for an estate?

The free check asks a few questions about the estate and tells you whether an IHT400 is needed, which schedules apply and which documents to gather. No sign-up.

Do the free check Start an estate inventory

Software to help you prepare your own IHT400. Not legal or tax advice. We do not apply for probate. Not affiliated with HMRC.

Common mistakes

Using the residence nil rate band to decide that the estate is excepted. HMRC says it must not be used for that test (Trusts and Estates Newsletter, August 2026).
Following box 51's cross-reference. It says "Schedule IHT405, box 7", but the current IHT405 sends its box 6 (the residence) to box 51 and box 7 (other land) to boxes 68 to 70.
Deducting the transferred nil rate band at box 92 or 93. It belongs in box 116, or box 2 of the IHT400 Calculation.
Assuming interest waits for HMRC's figure. It runs from the first day of the seventh month, whoever works out the tax; a payment on account can be made before the exact amount is known.

Common questions

How long do I have to send the IHT400?

HMRC’s form asks for it within 12 months of the date of death; the law allows 12 months from the end of the month of death. The tax is due sooner, by the end of the sixth month after the month of death, and interest runs after that.

Can HMRC work out the tax for me?

Yes. If you are filling in the IHT400 yourself without a solicitor or other adviser, you can tick the box under box 108 and HMRC will work out the tax.

Do I need an Inheritance Tax reference number?

Only if there is tax to pay. Apply online or on Schedule IHT422 at least 3 weeks before you send the IHT400.

Who signs the IHT400?

Each person delivering the account, such as the executors, signs the declaration on page 16. HMRC returns forms where the declaration is not completed correctly.

What if I do not know a value yet?

After making full enquiries you can use a provisional estimate, list those boxes in the declaration, and tell HMRC the final figure later on a corrective account (form C4).

How long does it take to get the probate code?

HMRC usually sends it within 20 working days of receiving the IHT400 or the payment, whichever is later.