UK Inheritance Tax Reference Number 2026/27 — IHT422 Guide

If an estate has Inheritance Tax to pay, the personal representative or adviser normally needs an Inheritance Tax reference number before sending the IHT400 and making the payment. HMRC’s current process uses the online IHT422 service for most non-trust cases. The applicant needs sign-in details or an email address, and should allow time for the reference to arrive before the payment or account is sent.

This is an administration guide, not an Inheritance Tax calculation. For the underlying thresholds, gifts, residence nil rate band and 40% rate, see the UK Inheritance Tax 2026/27 guide. The reference number identifies the HMRC payment or estate record; it does not decide whether tax is due.

What is an Inheritance Tax reference number?

The reference number is the identifier HMRC uses for an Inheritance Tax payment and related estate correspondence. It is different from an online estate report reference and should not be replaced by a probate or confirmation reference.

If you calculate that tax is due, HMRC’s procedure is to obtain the reference first, then send the IHT400 and supporting schedules and make the payment using the instructions for the estate. Using the wrong reference can delay allocation of the payment or cause it to be associated with the wrong record.

The reference is a process requirement. It does not confirm that HMRC has accepted the valuation, reliefs or tax calculation, and receiving one is not an approval of the estate account.

Who normally needs to apply?

The online IHT422 route is relevant to a personal representative or authorised adviser dealing with an estate where Inheritance Tax is payable or an IHT400 filing needs a reference. HMRC’s guidance says the online service is used to request a reference before sending form IHT400 and paying the tax.

You may not need to request a reference where there is no tax to pay, but the filing obligation can still depend on whether the estate qualifies as an excepted estate and on the facts of the death, gifts, trusts and reliefs. Do not treat “no reference required” as “no IHT paperwork required”.

An adviser should confirm who is authorised to act and keep the application details with the estate file. The reference belongs to the relevant estate or transfer, not to a general client profile.

How to apply online using IHT422

HMRC’s current IHT422 page links to the online service for requesting an Inheritance Tax reference. The service requires either sign-in details or an email address. The exact questions and confirmation flow are controlled by HMRC’s live form, so use the official service rather than relying on an old screenshot or a copied paper form.

Prepare the key estate details before starting, including the deceased’s information, the date of death, the applicant or adviser details and the intended payment or IHT400 context. Check names, addresses and identifiers carefully. A mismatch can make later correspondence harder to trace.

After the application, retain the confirmation and the reference number in the estate records. Use the reference exactly as HMRC instructs when paying or corresponding. Do not put an online estate report number, probate application number or an unrelated tax reference in its place.

When should you apply?

HMRC says you should get the Inheritance Tax reference number at least 3 weeks before making a payment. That is a planning minimum, not a guarantee that every estate will be processed in the same time. Apply earlier when valuations, bank payments, the Direct Payment Scheme or probate timing make the estate more complex.

The reference is only one part of the timetable. You may also need to complete the IHT400 and schedules, arrange a payment from the deceased’s bank or investment account, gather supporting evidence and meet the separate deadlines for the estate account. Keep the application, payment confirmation and submitted account together so that the file shows a continuous audit trail.

What if the payment is from the deceased’s account?

The Direct Payment Scheme may allow a bank, building society or investment provider to pay some or all of the Inheritance Tax from the deceased’s account. The reference number is still part of the process. GOV.UK’s current steps include getting the payment reference, completing form IHT423 for the institution and sending the IHT400 and supporting documents to HMRC.

The provider’s procedure can differ, and not every institution has to participate. Confirm its requirements before relying on the payment route. A Direct Payment Scheme request does not remove the need to identify the estate correctly or to submit the required account and schedules.

How do trusts differ?

Trust payments use a separate process. GOV.UK says the trustee should complete form IHT122 and post it to HMRC to request an Inheritance Tax reference for a trust; the trust route cannot use the online IHT422 service in the same way as most other payments.

Do not use the estate workflow for a trust charge simply because both involve Inheritance Tax. Identify whether the payment concerns a deceased person’s estate, a lifetime transfer or a trust, then use the form and payment instructions for that category.

Common reference-number mistakes

Frequently Asked Questions

Evidence and decision checks

A reliable uk inheritance tax reference number 2026 27 review starts by fixing the tax year and the date on which the relevant event happened. Record the person's or business's status, the income or transaction category, the amount before tax, tax already withheld, and any election or claim being relied on. Do not combine a headline figure with a final liability: the result can change when another income source, a payment date, an ownership interest or a qualifying condition is added.

Keep the source documents behind every important input. Depending on the subject, that may include payslips, invoices, bank statements, contracts, provider statements, travel records, HMRC notices, payroll submissions, valuations or correspondence. Where an amount is apportioned, write down the method and retain the underlying total. If a correction is made, preserve the original figure and explain the reason, date and evidence for the replacement.

Before relying on the result, check the current official guidance for the same tax year and jurisdiction. Distinguish enacted law from a consultation, draft measure, announcement or future proposal, and record the effective date. Reconcile the final estimate to the relevant return, payroll record or HMRC account. A calculator or explanatory guide can support a decision, but it cannot replace the eligibility test or the official filing and payment process.

Evidence and decision checks

A reliable uk inheritance tax reference number 2026 27 review starts by fixing the tax year and the date on which the relevant event happened. Record the person's or business's status, the income or transaction category, the amount before tax, tax already withheld, and any election or claim being relied on. Do not combine a headline figure with a final liability: the result can change when another income source, a payment date, an ownership interest or a qualifying condition is added.

Keep the source documents behind every important input. Depending on the subject, that may include payslips, invoices, bank statements, contracts, provider statements, travel records, HMRC notices, payroll submissions, valuations or correspondence. Where an amount is apportioned, write down the method and retain the underlying total. If a correction is made, preserve the original figure and explain the reason, date and evidence for the replacement.

Before relying on the result, check the current official guidance for the same tax year and jurisdiction. Distinguish enacted law from a consultation, draft measure, announcement or future proposal, and record the effective date. Reconcile the final estimate to the relevant return, payroll record or HMRC account. A calculator or explanatory guide can support a decision, but it cannot replace the eligibility test or the official filing and payment process.

Evidence and decision checks

A reliable uk inheritance tax reference number 2026 27 review starts by fixing the tax year and the date on which the relevant event happened. Record the person's or business's status, the income or transaction category, the amount before tax, tax already withheld, and any election or claim being relied on. Do not combine a headline figure with a final liability: the result can change when another income source, a payment date, an ownership interest or a qualifying condition is added.

Keep the source documents behind every important input. Depending on the subject, that may include payslips, invoices, bank statements, contracts, provider statements, travel records, HMRC notices, payroll submissions, valuations or correspondence. Where an amount is apportioned, write down the method and retain the underlying total. If a correction is made, preserve the original figure and explain the reason, date and evidence for the replacement.

Before relying on the result, check the current official guidance for the same tax year and jurisdiction. Distinguish enacted law from a consultation, draft measure, announcement or future proposal, and record the effective date. Reconcile the final estimate to the relevant return, payroll record or HMRC account. A calculator or explanatory guide can support a decision, but it cannot replace the eligibility test or the official filing and payment process.

Start with HMRC’s IHT422 online application and payment-reference guidance. For the tax calculation itself, use the Inheritance Tax Calculator→ and the broader UK Inheritance Tax 2026/27 guide.

Official sources

• HMRC — Apply for an Inheritance Tax reference (IHT422)
• GOV.UK — Pay your Inheritance Tax bill: get a payment reference number
• HMRC — Agent Update issue 146: changes to the Inheritance Tax reference process
• HMRC — Inheritance Tax manual: submitting the account and obtaining a grant