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IHT400

Also known as: Inheritance Tax Account, IHT Return Form

Definition

Form IHT400 is HMRC's detailed Inheritance Tax return that executors complete to report the full value of an estate and calculate any tax due.

This comprehensive form is required when an estate potentially owes Inheritance Tax or doesn't qualify for simplified reporting. Without completing it correctly, executors cannot obtain a Grant of Probate and the estate administration remains blocked.

What Does IHT400 Mean?

Under the Inheritance Tax Act 1984, form IHT400 must be completed as part of the probate process if the estate doesn't qualify as an "excepted estate." Generally, this means estates valued over £325,000 without full spouse exemption, or estates exceeding £3 million even when passing to exempt beneficiaries. The form must be submitted to HMRC within 12 months of death and before applying for a Grant of Probate.

Form IHT400 is an interactive PDF that must be completed using Adobe Reader—you cannot save partial progress, so executors need to gather all information before starting. The main form typically requires multiple supplementary schedules (numbered IHT401-IHT436) covering specific asset types: Schedule IHT405 for property, IHT406 for bank accounts, IHT411 for stocks and shares, and IHT403 for gifts made before death. Every asset and debt must be reported at market value on the date of death, including gifts made in the seven years before death.

An important procedural change took effect on 17 January 2024 for England and Wales. Executors no longer need to complete form IHT421 alongside the IHT400. Instead, after HMRC processes the IHT400 (typically 3-4 weeks for straightforward estates), they send an acknowledgment letter containing a unique code and confirmed estate values. Executors use this acknowledgment to apply for probate through the online portal. Northern Ireland still requires IHT421, and Scotland uses the same IHT400 form but calls the process "confirmation" rather than "probate."

The form's complexity varies significantly based on estate composition. Sarah's father James left an estate worth £480,000 including his house (£320,000), savings (£140,000), and a car (£20,000). As executor, Sarah completed the main IHT400 plus three schedules. Despite no tax being due—James's combined nil rate bands totaled £650,000—the form was still required because estates over £325,000 don't qualify as excepted estates. The IHT400 documented his unused allowances for future claims.

Common Questions

"Do I need to fill in an IHT400 form if the estate is worth £400,000 and everything goes to the surviving spouse?" Yes, you'll need to complete form IHT400 even though no Inheritance Tax is due. Estates valued over £325,000 don't qualify as "excepted estates" even when passing to a spouse, so HMRC requires the full form to record the value and confirm the spouse exemption applies.

"How long does it take HMRC to process an IHT400 form?" HMRC typically takes 3-4 weeks to process an IHT400 form, though this can extend to 8-12 weeks for complex estates or during busy periods. You'll receive an acknowledgment letter containing a unique code and confirmed estate values, which you need to apply for the Grant of Probate.

"Can I complete the IHT400 form myself or do I need a solicitor?" Many executors successfully complete IHT400 forms themselves for straightforward estates using HMRC's detailed guidance notes. However, consider professional help if the estate includes business interests, foreign assets, trusts, or complex gift arrangements. HMRC provides comprehensive instructions and a helpline (0300 123 1072) for specific questions.

Common Misconceptions

Myth: If no Inheritance Tax is due, I don't need to complete the IHT400 form

Reality: Many estates that owe no tax still require form IHT400. The form is required if the estate doesn't qualify as "excepted"—generally estates valued over £325,000, even if the entire estate passes to a spouse. The IHT400 is about reporting to HMRC, not just paying tax, and you need their acknowledgment to proceed with probate.

Myth: The IHT400 form is so complex that only professionals can complete it correctly

Reality: While the IHT400 is detailed and requires careful completion, thousands of executors successfully complete it themselves each year for straightforward estates. HMRC provides comprehensive guidance notes explaining each section, and their helpline offers support. Professional help becomes valuable for estates with business interests, complex trusts, foreign assets, or significant lifetime gifts.

Understanding IHT400 connects to these related concepts:

  • Inheritance Tax (IHT): The IHT400 is the form used to report and calculate this tax on estates.
  • Executor: The person legally responsible for completing the IHT400 and submitting it to HMRC.
  • Grant of Probate: The IHT400 must be completed and acknowledged before this can be issued.
  • HMRC: The government department that receives, processes, and issues acknowledgment letters for IHT400 forms.
  • Estate Valuation: Accurate valuation of all assets and debts is essential before completing the IHT400.
  • Understanding Inheritance Tax in the UK: Learn how the IHT400 fits into the broader inheritance tax framework and calculation process.
  • The Probate Process Timeline: Discover how IHT400 submission and HMRC processing affects your overall probate timeline.
  • Executor Responsibilities and Duties: Understand why completing the IHT400 accurately is one of your key legal obligations.

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Legal Disclaimer: This glossary entry provides general information about UK legal terminology and does not constitute legal advice. While this explanation provides general guidance about form IHT400, inheritance tax calculations and form completion can be complex. HMRC provides detailed official guidance notes with the form, and their Inheritance Tax helpline (0300 123 1072) can answer specific questions. For complex estates or advice specific to your situation, consult a qualified solicitor or tax advisor.