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Discovering you have missed an asset during probate is stressful. The key is to act promptly and correctly. HMRC publishes a form for the purpose — the C4 corrective account, or C4(S) in Scotland — and the penalty rules distinguish sharply between an honest omission and a careless or deliberate one. This guide explains what to do, depending on how far through the process you are. It describes the England and Wales route; the Scottish differences are noted where they arise. For a broader look at what can go wrong during probate, see our guide to common probate mistakes executors make.
Before deciding what to do, it helps to understand why assets are missed in the first place. The most frequently overlooked assets are:
For a comprehensive list, see our guide to what counts as an asset for probate in the UK.
The right course of action depends on where you are in the probate process.
If you have submitted the IHT400 and PA1P but the grant has not yet been issued, you can correct the application before the grant is released. Contact HMRC's Inheritance Tax team (0300 123 1072) to notify them of the additional asset and ask how to amend your IHT submission. Contact HMCTS Probate to update the gross and net estate values on the PA1P if they have changed. (PA1P and PA1A are the England and Wales forms; in Scotland the equivalent stage is the inventory lodged with the sheriff court for confirmation, and Northern Ireland applies through the Probate Office in Belfast.)
Correcting at this stage is the cheapest point to do it. There is no penalty for an inaccuracy where you took reasonable care, and coming forward before HMRC raises the point counts as an unprompted disclosure. It is not free, though: if the missed asset means Inheritance Tax was underpaid, interest still runs from the original due date, whether or not the grant has been issued.
Where an IHT400 was delivered, the correction goes on a C4 corrective account. In Scotland the equivalent is form C4(S), a corrective inventory and account, which is also what you use when an additional grant of confirmation is needed because assets were left out of the original inventory or their description has changed. The C4 is a straightforward form that allows you to:
The C4 must be signed by the executor(s) — HMRC expects everyone who signed the IHT400 to sign it — and sent to HMRC Inheritance Tax. HMRC will issue a revised calculation showing any additional IHT due, together with any interest that has accrued. You then pay the balance to settle the account.
There is a deadline, and it is statutory. Section 217 of the Inheritance Tax Act 1984 provides that anyone who has delivered an account and later discovers it to be defective in a material respect must deliver a further account within six months of that discovery. The clock runs from when you found out, not from the death or the grant.
Submitting a C4 corrective account is not an admission that you made a deliberate error. HMRC publishes the form, its internal manual sets out how its staff handle one, and the law requires you to send it — it is the standard mechanism for updating the IHT record during estate administration, not a confession.
Whether the missed asset results in additional IHT depends on the estate's position relative to the nil-rate band.
IHT is due by the end of the sixth month after the month of death (the "due date"). Interest accrues on any unpaid IHT from that date at HMRC's late payment rate, which is linked to the Bank of England base rate plus a margin and so changes. It has been 7.75% a year since 9 January 2026 — check the HMRC rate table for the rate in force when you are reading this.
At that rate, if you discover a missed asset a year after the due date and the additional IHT on it is £10,000, you would owe roughly £10,775 in total — the tax plus about £775 of interest. The interest is not a penalty; it is the cost of the money having been paid late.
For more detail on how IHT interest works, see our guide to probate delays and IHT interest.
If you have distributed the estate to beneficiaries and then discover a missed asset, the situation is more complicated — but still manageable. You have two issues to address simultaneously:
Recovering funds from beneficiaries who have already received more than their correct entitlement (because IHT was underpaid) is legally possible but practically difficult. In most cases, where the beneficiary is cooperative and the amount is modest, this can be resolved informally. If the beneficiary is uncooperative, you may need legal advice.
This is one of the strongest reasons not to distribute the estate too hastily. See our guide on executor personal liability in the UK for more on the risks of premature distribution.
For a genuinely missed asset — one you did not know about and could not reasonably have found — there is typically no penalty. HMRC's penalty regime applies to careless or deliberate errors, not to honest omissions that are corrected promptly.
Under Schedule 24 to the Finance Act 2007 a careless inaccuracy carries a penalty of up to 30% of the tax. Where you come forward before HMRC raises the point — an unprompted disclosure — that 30% can be reduced to as little as 0% depending on the quality of the disclosure; if HMRC prompts you first, the reduction stops at 15%. Deliberate errors are treated far more harshly, at up to 70% (or 100% where concealed). The practical point is that coming forward first is worth a great deal. See our guide on the consequences of making a mistake on your probate application.
For executors still in the early stages of administration, a systematic asset search at the outset prevents most omissions:
No — you can complete and submit the C4 yourself. HMRC provides guidance notes with the form. However, if the missed asset significantly changes the IHT position, or if you are concerned about the interest and penalty implications, professional advice may be worthwhile before submitting.
The C4 exists to correct an IHT400. If an IHT400 was delivered, section 217 requires a further account where the original was defective in a material respect, so submit one even if the additional asset creates no further liability. If the estate was reported as an excepted estate — where, for deaths on or after 1 January 2022, the values go in the probate application rather than on a separate IHT form — there is no IHT400 to correct, and you should ask HMRC what it wants rather than assuming a C4 is the right form.
Contact NS&I to claim the Premium Bond as executor, then submit a C4 to update the IHT400 (within six months of finding it, under section 217). If the additional value pushes the estate over the nil-rate band or increases the taxable estate, additional IHT and interest will be due. If the estate remains below the nil-rate band, there is no additional IHT — but the record still needs updating.
There is a deadline, and it is six months. Section 217 of the Inheritance Tax Act 1984 requires anyone who has delivered an account and then discovers it to be defective in a material respect to deliver a further account within six months of that discovery. Interest also accrues from the original IHT due date, so the sooner you submit, the less you pay.
Separately, section 240 limits how long HMRC has to recover underpaid tax: four years from the later of the date the tax was paid and accepted or the date it became due, six years where the loss of tax was brought about carelessly, and twenty years where it was brought about deliberately. Note that the period runs from payment or the due date, not from the date the account was delivered.
Yes, legally — if beneficiaries received more than they should have because the IHT bill was understated, they have received funds that should have been retained for HMRC. In practice, if a beneficiary cooperates, the recovery can be done informally. If they refuse, legal action may be required. This situation is best avoided by not distributing the estate before the IHT position is fully settled.
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