An old dividend cheque turns up in a drawer. A solicitor mentions a gift from years before the death that never made it onto the account. A share valuation turns out to be wrong. None of this stops at the grant: an Inheritance Tax account already sent to HM Revenue and Customs (HMRC) can still need correcting, and the form for it is C4.
What form C4 is
Form C4 is HMRC’s corrective account. HM Revenue and Customs (HMRC) says taxpayers or agents complete it to tell them about amendments to the original account (HMRC IHTM10701, checked 1 November 2026). The form covers changed asset values, assets left off the IHT400, and changed liabilities, exemptions or reliefs (Form C4 (PDF), checked 1 November 2026).
All accountable persons have to sign the C4 themselves. HMRC’s manual says an agent acting on their behalf must not sign the form (HMRC IHTM10703, checked 1 November 2026). The form is downloaded from GOV.UK, completed on screen, printed and posted to HMRC (GOV.UK: Inheritance Tax corrective account (C4), Inheritance Tax: corrective account, checked 1 November 2026).
If the estate is in Scotland, a different form applies. HMRC’s manual says form C4(S) doubles as a corrective inventory, used to get an Eik to Confirmation (HMRC IHTM10701, checked 1 November 2026). GOV.UK describes this as an additional grant of confirmation for Scottish assets whose description has changed or that were not originally included (GOV.UK, Inheritance Tax: corrective account, checked 1 November 2026).
The legal duty and the six-month deadline
The duty comes from statute. Section 217 of the Inheritance Tax Act 1984 says that if you discover an account you delivered is defective in a material respect, you must deliver a further account within six months of that discovery (Inheritance Tax Act 1984, s.217, checked 1 November 2026).
HMRC’s manual repeats this as the strict legal position, describing the further account as a corrective account and citing the same six-month figure (HMRC IHTM10805, checked 1 November 2026). In practice, HMRC does not hold most executors to that deadline, which the next section explains.
Reclaiming tax already paid is a different section of the Act, with a longer deadline. If you claim within four years of the payment, section 241 says HMRC must repay any excess tax (Inheritance Tax Act 1984, s.241, checked 1 November 2026). The C4 is still the form used to put the claim to HMRC.
HMRC lets you save up smaller amendments
HMRC does not expect a C4 within six months of every discovery. Where certain conditions are met, HMRC says it lets customers save up amendments and tell it about them in one go, rather than filing a corrective account each time something new turns up (HMRC IHTM10701, checked 1 November 2026).
The concession does not apply, and HMRC expects to be told within six months instead, where any of the following are true (HMRC IHTM10806, checked 1 November 2026):
- HMRC has opened a compliance check into the estate
- the estate includes a qualifying interest in possession or a gift with reservation
- the overall change in value is more than £50,000 before reliefs
- the change is to land, buildings or unlisted shares
- it is a loss-on-sale-of-land or loss-on-sale-of-shares claim
- assets on which tax is paid by instalments have been sold
Where the concession does apply, HMRC says to send form C4 when you believe the amendments are final, or 18 months after the death, whichever is sooner. It will not charge a penalty for a late corrective account on those terms, but interest on any unpaid tax still runs, and a payment on account can stop it building up further (HMRC IHTM10806, checked 1 November 2026).
Gifts found after the account went in
A gift found after the account was sent goes on schedule IHT403, filed together with form C4. HMRC says the schedule covers any gift the deceased made on or after 18 March 1986 (GOV.UK: IHT403, checked 1 November 2026), whatever the date of the original account.
The seven-year rule, and the exemptions that take smaller gifts out of the schedule, are already covered on the site’s gifts and the 7-year rule page. They apply the same way whether a gift is reported at the first account or found years later.
Penalties for getting it wrong
HMRC can penalise an inaccurate Inheritance Tax account, even where the error was genuinely missed at the time. An account delivered under section 216 or 217 of the Inheritance Tax Act 1984 falls within Schedule 24 to the Finance Act 2007.
This is the general penalty regime for inaccurate documents sent to HMRC (Finance Act 2007, Schedule 24, checked 1 November 2026).
Schedule 24 grades the error. A “careless” inaccuracy, meaning a failure to take reasonable care, carries a penalty of up to 30% of the extra tax. A deliberate but not concealed error carries up to 70%, and a deliberate and concealed one up to 100%.
An innocent mistake can turn careless later. If you discover the error and do not take reasonable steps to tell HMRC, the law treats the inaccuracy as careless from that point, which is the position of an executor who finds an old gift or an uncashed cheque and does nothing about it.
Disclosing the error yourself, before HMRC starts checking, brings the penalty down sharply. The minimum for an unprompted disclosure of a careless error is 0%, against 15% if HMRC asks first. Sending the C4 promptly, rather than waiting to be found out, is what earns that reduction.
Interest on the extra tax
Interest runs on any extra tax whether or not a penalty applies, and whether you save up amendments or report at once. HMRC’s guidance says it will still charge interest on unpaid tax where an executor chooses to save up amendments, and that a payment on account can stop it building up further (HMRC IHTM10806, checked 1 November 2026).
The rate is the same one that applies to the original account. HMRC’s rates table shows 7.75% for late payment from 9 January 2026, already covered on the site’s Inheritance Tax forms page, which also explains when the original tax is due.
A dividend declared but unpaid, and a cheque never cashed
Some shares carry a dividend that was due but not yet paid when the person died, marked “XD” by the stock exchange. GOV.UK says to include the net value of that dividend, after Income Tax, by multiplying the number of shares by the dividend per share (GOV.UK: Valuing stocks and shares for Inheritance Tax, checked 1 November 2026).
A cheque for a dividend that was paid before death but never banked is different again. It is money the deceased was owed, which GOV.UK lists as an asset in the same way as unpaid wages or refunds from household bills (GOV.UK: Valuing the assets, Estimate the estate’s value, checked 1 November 2026). If it was left off the original account, it is reported through the C4 process above.
How a registrar such as Computershare, Equiniti or Link reissues an old, uncashed cheque is a matter for that company’s own procedures, not a government process. Ask the registrar named on the cheque directly.
Where to ask
Two questions here have no published answer. Whether a deadline applies to a first full account once an estate turns out not to be excepted after all, and whether a new or amended grant is needed for an asset found later, are both best put to the people who decide them.
HMRC’s Inheritance Tax helpline, 0300 123 1072, Monday to Friday, 9am to 5pm, answers questions about the forms and the rules on an individual estate (GOV.UK, Inheritance Tax: general enquiries, checked 1 November 2026).
For whether the grant itself needs to change, the Courts and Tribunals Service Centre, which handles probate registry enquiries, can be reached on 0300 303 0648, Monday to Friday, 9am to 1pm (GOV.UK, Applying for probate: after you've applied, checked 1 November 2026). Our how long probate takes page has its webchat and email address too.