A practical walkthrough of the IHT400 inheritance tax account, when it is needed, what information to gather, and how to avoid common HMRC delays.
This guide is part of ProbateHelp's Inheritance Tax guide cluster. Estimated reading time: 25 min.
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Use the current GOV.UK IHT400 page and form notes before you submit. GOV.UK provides the IHT400 as an interactive form that you complete before printing, and says you should gather your information first because you cannot save a partly completed form. Check the current HMRC instructions before sending anything.
Use form C4 to report amendments to an IHT400 when too much or too little tax was reported. Pay undisputed additional tax promptly because interest may run from the original due date. HMRC's penalty decision depends on the facts, including the care taken and how quickly an error is corrected.
Not always. Many estates can use the simplified excepted estates route (completing a declaration on the probate application form) rather than the full IHT400. The rules changed in January 2022 and more estates now qualify for the simplified route. Check the current excepted estates thresholds on gov.uk before deciding which route applies.
You should expect extra time when an IHT400 is needed, because HMRC must process the tax account before the England and Wales probate application can move forward. GOV.UK says you must submit the IHT400, start paying any Inheritance Tax due, and wait for HMRC to send the unique code before applying for probate.
Yes, if the estate is not excepted and you have submitted IHT400. GOV.UK says you must submit IHT400 before applying for probate, start paying Inheritance Tax if any is due, and wait for HMRC to send the unique code. You then enter that code in the online or paper probate application.
Some tax on land, businesses, qualifying shares and APR/BPR property can be paid in 10 annual instalments. Interest rules depend on the asset. For qualifying APR/BPR property inherited from 6 April 2026, the outstanding balance is interest-free while instalments are paid on time and the property is not sold. A sale normally makes the unpaid balance due.