If you are dealing with an estate after someone has died, you may come across the IHT400 form and wonder whether you must complete it before applying for probate. The answer is: sometimes, but not always.
Whether you need IHT400 depends on the type of estate, its value, and whether inheritance tax is payable. This guide explains when the form is required, when it is not, and where it fits into the probate process. If you already know you need it, our guide to the IHT400 form walks through the form itself, its schedules and how to submit it.
What is the IHT400 form?
IHT400 is the full inheritance tax return used to report detailed information about an estate to HMRC. It covers the value of assets, liabilities, gifts made before death, and any reliefs or exemptions claimed.
It is not required for every estate. Since January 2022, the excepted estate rules have been significantly simplified, meaning that the vast majority of non-taxpaying estates that need probate now qualify for a streamlined process that does not involve IHT400 at all. Please note that this is subject to the date of death test, not a date of application test. Executors dealing with an older death still fall under the previous rules in force before 1 January 2022.
When you do need to complete IHT400
You must complete IHT400 if there is inheritance tax to pay, or if there is no inheritance tax to pay but the estate does not qualify as an excepted estate.
In practice, this applies when:
- Inheritance tax is payable
- The estate does not qualify as an excepted estate
- The deceased made chargeable gifts in the seven years before death totalling more than £250,000
- The deceased made any chargeable gift that was not a specified transfer, whatever its value. Specified transfers are limited to cash, quoted shares and securities, and land with its furnishings and personal goods, so a small gift of unquoted shares or a transfer into a trust disqualifies the estate on its own
- The deceased gave something away but carried on benefiting from it. A gift with reservation of benefit disqualifies the estate at any value
- The estate includes foreign assets worth more than £100,000
- The estate is worth more than £3 million, even if left to a spouse or charity
- The deceased held assets in more than one trust, which disqualifies outright regardless of value, or in a single trust above the permitted limits (£250,000 gross for a low value estate; £1 million gross and £250,000 net for an exempt estate)
- Business Relief or Agricultural Relief is being claimed in more complex situations
You must send the IHT account to HMRC and pay at least the first instalment of any tax due before you can apply for probate. HMRC will then send you a unique code that you need to complete your probate application. Allow for the wait: HMRC normally issues that code within 20 working days of receiving the IHT400 or the tax payment, whichever is later, and executors routinely misjudge the probate timetable because of it.
When you do not need to complete IHT400
You do not usually need IHT400 if the estate qualifies as an excepted estate. An excepted estate is one that meets specific conditions set by HMRC, allowing simplified reporting within the probate application itself rather than a full separate return.
There are three categories of excepted estate: low-value estates, exempt estates (passing to a spouse or charity), and the estates of people who were not long-term UK resident. That third category used to be based on domicile; for deaths on or after 6 April 2025 the test is long-term UK residence, and the UK estate must consist only of cash or quoted shares and securities with a gross value not exceeding £150,000.
This typically applies where:
- The gross value, including chargeable lifetime transfers and lifetime gifts to a spouse or charity, is at or below the available nil-rate band
- For an exempt estate, the gross value does not exceed £3 million and the net chargeable value, after deducting liabilities and spouse or charity exemption only, does not exceed the nil-rate band
The available nil-rate band is £325,000, or more where a transferable nil-rate band is claimed from one predeceased spouse or civil partner. The familiar £650,000 figure only applies where the whole of the first spouse’s band was unused. For deaths on or after 1 January 2022 a partial claim is allowed, so the ceiling is £325,000 plus whatever percentage transfers, which may be well below £650,000.
One point that catches people out on the exempt category: only spouse, civil partner and charity exemption can be deducted in working out the net chargeable value. The residence nil-rate band, Business Relief and Agricultural Relief cannot. An estate can therefore have no inheritance tax to pay and still need a full IHT400.
Executors of an excepted estate still apply for probate in the normal way but use a simpler declaration on the probate application rather than completing the IHT400. There is then a prescribed period of 60 days from the issue of the first grant during which HMRC can issue a written notice asking for further information or documents. If no notice is issued, everyone personally liable is automatically discharged from inheritance tax liability at the end of that period. That discharge does not apply where information was false, material facts were withheld, or further property later comes to light that breaches the conditions. Our guide to excepted estates sets the conditions out in full.
How IHT400 fits into the probate process
When inheritance tax and probate interact, the sequence of events typically looks like this:
- Value the estate, including property, savings, investments, and debts
- Establish whether the estate is an excepted estate or requires a full IHT400
- If IHT400 is required, complete it and submit it to HMRC
- Pay any inheritance tax due (or at least the first instalment)
- Receive the HMRC reference code needed to apply for probate
- Apply for probate; the grant allows the estate to be administered
There are two distinct deadlines that catch executors out. You must submit IHT400 within 12 months of the end of the month in which the person died, or within three months of first acting as personal representative if that is later. However, inheritance tax is generally due six months after the end of the month in which the person died, and interest runs on unpaid tax after that point. In practice, most executors aim to submit the form and pay the tax at the same time, well before the six-month mark.
Valuations must be accurate
Accurate valuations matter whether or not IHT400 is required. HMRC expects assets, particularly property and investments, to be valued realistically at the date of death.
Undervaluing assets can lead to delays, interest charges, or penalties. Overvaluing them may result in paying more tax than necessary. RICS Red Book valuation is advisable for any property in a taxpaying estate, or where the liability is borderline, since HMRC will challenge estate agent estimates.
Paying inheritance tax before probate
Executors face a common problem: you often need to pay the tax to get probate, but you cannot access the deceased’s money without probate. This creates a genuine cash-flow challenge.
There are some practical options. The Direct Payment Scheme (form IHT423) allows participating banks, building societies, and NS&I to release funds from the deceased’s accounts directly to HMRC. For property and certain other assets that may take time to sell, you can choose to pay inheritance tax in annual instalments over 10 years. Interest is normally charged on the outstanding balance, though from 6 April 2026 the balance on certain assets qualifying for Business Relief or Agricultural Relief is interest-free.
Where none of these options cover the full amount, executors sometimes consider an inheritance tax loan. IHT loans are designed specifically for this situation and are repaid once probate has been granted and estate assets become available.
If you pay inheritance tax from your own funds before probate is granted, you can usually recover that sum from the estate once the grant is issued.
Get help with IHT400 and probate
Working out whether IHT400 is required, valuing an estate correctly, and paying inheritance tax on time involves real complexity, particularly when deadlines are pressing.
The Probate Network connects you with experienced probate professionals who can explain which forms are needed, when tax is payable, and what options are available when funds are tied up in the estate.
If you are unsure whether you need to complete IHT400 before applying for probate, use The Probate Network to find a probate specialist.
Frequently asked questions
Does every estate need to submit IHT400 to HMRC?
No. Most estates in England and Wales qualify as excepted estates and do not need a full IHT400. Instead, the executor provides a summary of the estate’s value as part of the probate application. More than 90% of non-taxpaying estates that need probate fall into this category. IHT400 is only required where inheritance tax is payable, or where the estate does not meet the conditions for excepted estate status.
What are the key conditions for an estate to be excepted?
The main categories are: a low-value estate where the gross value does not exceed the available nil-rate band, which is £325,000 plus any percentage transferred from one predeceased spouse or civil partner, reaching £650,000 only where none of their band was used; an exempt estate where the gross value does not exceed £3 million and the net chargeable value after spouse, civil partner or charity exemption is within the nil-rate band; and the estates of people who were not long-term UK resident, where the UK estate is limited to cash and quoted securities not exceeding £150,000. Additional conditions apply in each category, including limits on foreign assets, trust assets and lifetime gifts, and a gift with reservation of benefit rules the estate out entirely, so always check the full HMRC criteria or take professional advice.
Will pensions need to be included in the IHT400 from 2027?
Yes, for deaths on or after 6 April 2027. The Finance Act 2026 confirmed that most unused pension funds and pension death benefits will be brought within the value of the deceased’s estate for inheritance tax purposes from that date. Currently, most pension funds sit outside the estate. For deaths before 6 April 2027, the existing rules continue to apply. Speak to a qualified professional if this may affect the estate you are administering.
This article is for general guidance only and does not constitute legal, tax, or financial advice. Rules and thresholds can change and every estate is different. For advice on your own circumstances, speak to a qualified professional. You can book a free legal consultation through The Probate Network.
