HMRC Inheritance Tax Reference Number: How to Apply Before Paying IHT
You cannot pay inheritance tax to HMRC without an IHT reference number — and you cannot get probate without paying IHT. Here is how to apply, how long it takes, and the exact order to do everything in.
The IHT-Probate Deadlock — and How to Solve It
The three-way catch
You need an IHT reference number before HMRC will accept an IHT payment or IHT400 submission.
You need to pay IHT (or confirm no IHT is due) before the Probate Registry will issue the grant.
You need the grant of probate before you can access the deceased’s bank accounts to pay IHT from estate funds.
The solution: HMRC Direct Payment Scheme (form IHT423)
Banks can pay HMRC directly from the deceased’s accounts without the grant — breaking the deadlock at step 3. You must have the IHT reference number first.
Who Needs an IHT Reference Number?
You DO need a reference number
- → Gross estate over £325,000 (even if exempt reliefs bring net IHT to zero)
- → Chargeable gifts made in the 7 years before death
- → Estate includes a trust interest or foreign assets requiring IHT400
- → You are submitting form IHT400 for any reason
You do NOT need a reference number
- → Estate qualifies as an excepted estate (see FAQs)
- → Gross estate under £3 million (deaths from 1 Jan 2022) with no complex features
- → You are using the IHT declaration within the online probate application
How to Apply for an IHT Reference Number
Apply online via GOV.UK
Search 'Apply for Inheritance Tax reference number' on GOV.UK and use the HMRC online IHT service. You can also apply via paper form IHT422 by post to HMRC Inheritance Tax, Ferrers House, PO Box 38, Castle Meadow Road, Nottingham, NG2 1BB — but online is faster.
Information needed
Deceased's full name, date of birth, and date of death. Deceased's National Insurance number (find on P60, payslips, correspondence with HMRC or DWP). Your name, address, and role (executor or administrator). Whether the estate has a UK-based solicitor acting.
Wait approximately 3 weeks
HMRC posts the reference number to the address provided. Allow 3 weeks from submission. Apply as soon as you have confirmed the estate is not an excepted estate — do not leave this until the last minute as you cannot pay IHT without it.
Use the reference on all IHT documents
Quote the IHT reference number on form IHT400, form IHT423 (Direct Payment Scheme), all cheques or bank transfer payments to HMRC, and all correspondence about this estate. HMRC's IHT reference number is different from the HMRC reference on self-assessment correspondence.
The Correct Order of Operations for IHT + Probate
| Step | Action | Timing |
|---|---|---|
| 1 | Apply for IHT reference number (online or form IHT422) | As soon as non-excepted estate confirmed; ~3 weeks to receive |
| 2 | Value all assets and liabilities (run in parallel with step 1) | Months 1–3 after death |
| 3 | Complete form IHT400 and supplementary schedules | After reference number received and valuations complete |
| 4 | Submit IHT400 to HMRC and request form IHT421 (confirms IHT position to Probate Registry) | As soon as IHT400 is complete |
| 5 | Pay IHT due using Direct Payment Scheme (IHT423) from deceased's accounts, or personal funds, or executor loan | Must be paid before probate; use DPS to avoid grant-before-payment deadlock |
| 6 | Apply for grant of probate (PA1P) or letters of administration (PA1A) with IHT421 confirmation | After IHT confirmed paid/not due; current wait 8–16 weeks |
| 7 | Collect estate assets using grant; reimburse any personal IHT payment | After grant issued |
Frequently Asked Questions
What is an HMRC Inheritance Tax reference number?
An HMRC Inheritance Tax reference number is a unique identifier (typically in the format IHT followed by digits) that HMRC assigns to a specific estate. You must have this reference number before you can: (1) Pay IHT to HMRC; (2) Submit form IHT400 (the full IHT account); (3) Use the Direct Payment Scheme (form IHT423) to pay IHT directly from the deceased's bank accounts. The reference number links all IHT correspondence, payments, and forms to the correct estate in HMRC's system. Without it, HMRC cannot process your payment and the Probate Registry cannot confirm that IHT has been paid.
Who needs to apply for an IHT reference number?
You need an IHT reference number if: (1) The gross value of the estate (before deductions) exceeds the nil-rate band threshold (currently £325,000 — even if the net taxable estate is below the threshold after reliefs and exemptions); (2) The estate includes chargeable transfers made in the 7 years before death; (3) You are completing form IHT400 for any other reason (e.g. the estate has foreign assets, contains a trust interest, or is not an excepted estate for other technical reasons). You do NOT need an IHT reference number if the estate qualifies as an excepted estate and you are using the simplified IHT205/IHT207 route (for deaths before 1 January 2022) or the online IHT declaration route (for deaths on or after 1 January 2022, where the estate value is below the relevant threshold and the estate meets all excepted criteria).
How do I apply for an HMRC IHT reference number?
The easiest method is to apply online via the HMRC online IHT service (search 'Apply for an Inheritance Tax reference number' on GOV.UK). You will need: (1) The deceased's full name, date of birth, and date of death; (2) The deceased's National Insurance number; (3) Your own details (as the executor or administrator applying); (4) The executor or administrator's contact address for HMRC correspondence. Once submitted, HMRC issues the reference number by post (or online if you used the Government Gateway). Allow approximately 3 weeks. Because HMRC sends the reference by post, apply as soon as you have confirmed the estate is not an excepted estate — do not wait until the week you need to pay IHT. You can also apply by post using form IHT422 (Application for an Inheritance Tax reference number), sent to HMRC Inheritance Tax, Ferrers House, PO Box 38, Castle Meadow Road, Nottingham, NG2 1BB.
What is the order of operations for IHT and probate?
The IHT-probate sequence is a chicken-and-egg problem that catches many executors out: (1) You need the IHT reference number before you can pay IHT; (2) You need to pay IHT before the Probate Registry will issue a grant; (3) You need the grant before you can access the deceased's accounts to pay IHT. The solution to step 3 is the HMRC Direct Payment Scheme: banks can pay HMRC directly from the deceased's accounts using form IHT423 — you don't need the grant first. The correct order is therefore: (a) Apply for IHT reference number (3 weeks); (b) Value assets and complete IHT400 (can run in parallel with step a); (c) Submit IHT400 to HMRC; (d) Use IHT423 to pay IHT direct from deceased's bank accounts (or pay from your own funds); (e) Once HMRC confirms IHT is paid, apply for probate using form PA1P or PA1A; (f) Probate Registry issues grant; (g) Use grant to collect all estate assets and reimburse yourself if you paid IHT personally.
What if the estate is an excepted estate — do I still need an IHT reference number?
No. If the estate qualifies as an excepted estate, you do not need to submit form IHT400 or obtain an IHT reference number. For deaths on or after 1 January 2022, the excepted estate threshold is: (a) For UK-domiciled deceased with no prior chargeable transfers: gross estate value under £3 million (and no more than £1 million in exempt transfers to spouse/civil partner and charities); or (b) Estates qualifying under other excepted criteria (e.g. small excepted estates where gross value is under £650,000 and transferable nil-rate band is available). In these cases, you complete the IHT declaration in the probate application itself. The rules were significantly relaxed for deaths after January 2022 — most modest estates are now excepted and avoid the IHT400 process entirely.
A Good Will Makes IHT Planning Easier
Your will can direct assets to a spouse (spouse exemption), charity (charity exemption), or into a qualifying trust — all reducing IHT. The WillSafe kit includes IHT planning guidance from £19.97 for England and Wales.