How to Complete the IHT400 Form: Step-by-Step Walkthrough

Do You Need the IHT400 at All?

You only complete the IHT400 when the estate is notan "excepted estate". For deaths on or after 1 January 2022, excepted estates no longer file a separate form at all. The old short form, IHT205, has gone. Instead, you simply report the estate's headline figures within the probate application itself.

Broadly, an estate is likely to need the full IHT400 if any of these apply (the GOV.UK checker gives a definitive answer):

• Inheritance tax is actually due
• The estate is over £325,000 and does not pass wholly to a spouse, civil partner or charity
• The deceased made substantial gifts in the 7 years before death
• There are trusts, or significant foreign assets
• You are claiming certain allowances, such as the residence nil-rate band, that require a claim form

Before starting, it helps to understand the allowances themselves. Our inheritance tax guide for 2026-27 covers the £325,000 nil-rate band, the residence nil-rate band of up to £175,000, and the unlimited spouse exemption.

Before You Start: Documents Needed

Gather these before beginning the form. For detailed guidance on property values, see our guide on valuing an estate for probate:

• Death certificate
• Will (if there is one)
• Property valuations
• Bank statements (date of death balances)
• Investment valuations
• Pension statements
• Life insurance policy details
• Vehicle valuations
• Mortgage and debt statements
• Details of gifts in the last 7 years

Create a spreadsheet listing all assets and debts. This becomes your reference and makes the arithmetic much easier to check.

Completing IHT400: Section by Section

About the deceased

The opening pages ask for basic information:

• Full name, date of birth, date of death
• National Insurance number
• Last address
• Marital status
• Domicile (UK for most people)
• Occupation

Executor or administrator details

• Your name and address
• Contact details (phone, email)
• Relationship to the deceased

UK assets

List all UK assets with values at the date of death:

• Property (detailed on schedule IHT405)
• Bank accounts (each box number matters, so go slowly)
• Savings and investments
• Personal belongings
• Vehicles

Critical: use date-of-death values, not current values.

Debts and liabilities

• Mortgage balance
• Loans and credit cards
• Funeral expenses
• Outstanding bills

Gifts and transfers

List gifts made in the 7 years before death:

• Gifts beyond the annual exemptions
• Transfers into trusts
• Gifts with reservation of benefit

Exemptions and reliefs

• Spouse or civil partner exemption (unlimited)
• Residence nil-rate band (up to £175,000). See our RNRB guide for eligibility
• Business or agricultural relief
• Charitable gifts

Calculating the tax

1. Total assets minus debts = net estate
2. Minus exemptions (spouse, charity)
3. Minus the £325,000 nil-rate band plus any residence nil-rate band
4. = taxable amount, charged at 40%

Declaration and schedules

• List which schedules you are including
• Sign the declaration (all executors who are applying must sign)

IHT400 Schedules: Which Ones Do You Need?

Schedules are supplementary sheets, one per type of asset or claim. You only complete the ones that apply. We have detailed guides for the most common:

A common combination: IHT400 + IHT405 + IHT406 + IHT407 + IHT419 + IHT435 for an estate with a house, bank accounts and a residence nil-rate band claim.

Common IHT400 Mistakes to Avoid

Submitting IHT400 to HMRC

The IHT400 pack is submitted by post. Send the completed form and schedules to HMRC Inheritance Tax, BX9 1HT. Tracked or recorded delivery is sensible, since the pack contains a lot of work you would not want to repeat.

Include with your submission

• Completed IHT400 and all relevant schedules
• Any documents the form or schedules specifically ask for

Keep your valuations, bank letters and calculations on file. HMRC does not need every supporting document up front, but it can ask for evidence later, and you will want it to hand if a query arrives.

The 20 working day wait

After you send the IHT400, you must wait 20 working days (roughly a month) before applying for probate. This gives HMRC time to process the account and pass what the probate registry needs across. Applying early risks your probate application being put on hold.

Paying Inheritance Tax

When it's due: by the end of the sixth month after the month of death. After that, HMRC charges interest on the unpaid amount.

Tax, or at least a first instalment, must normally be paid before the grant of probate is issued. This surprises many executors, because the estate's money is often locked away at exactly that point. There are established routes around it:

• Direct Payment Scheme (form IHT423):banks and building societies pay HMRC directly from the deceased's accounts, before probate
• Instalments on property: tax attributable to a house or land can be paid in annual instalments over up to 10 years, though interest is charged on the outstanding balance
• Paying personally and reclaiming from the estate later

Our guide to paying inheritance tax before probate walks through each option.

After Submission: Applying for Probate

Once the 20 working days have passed:

• Apply for probate online or by post, confirming that you have sent an IHT400 to HMRC
• HMRC may write with queries about valuations or gifts. Respond promptly, with evidence, to keep things moving
• Keep all records. HMRC can raise questions about an estate's tax position years later, and having the paperwork protects you as executor

Next step: apply for probate.

Getting Professional Help

Consider professional help if:

• There are business or agricultural assets
• There are foreign assets or trusts
• The gift history is complicated
• You are unsure about any section

Fees vary widely, so get quotes. Reasonable professional fees for administering the estate are generally payable from the estate rather than your own pocket.

Frequently asked questions