How to use form 64-8 to authorise a solicitor or accountant to deal with HMRC
If you have instructed a solicitor, accountant, or other professional to deal with HMRC about the estate, they cannot do anything until you have signed a 64-8.
It is a short, simple form — but without it, HMRC will not speak to them.
This walkthrough covers what the form asks for, which taxes to specify, what happens if there are multiple executors, and the difference between a 64-8 and the online 'agent authorisation' system.
✓ Official source checked 2 September 2026 · GOV.UK last updated that page 24 July 202664-8 on GOV.UK ↗
United Kingdom·Informational, not legal or financial advice·Official source: GOV.UK
✓Official form · always current
This is the same official 64-8 file HM Revenue & Customs publishes on GOV.UK — the link below fetches the current version live from GOV.UK the moment you click it, so it can never go out of date.
Current version: July 2026 · confirmed on GOV.UK 2 September 2026
This walkthrough takes form 64-8 field by field, in plain English. Most of the form is administrative; the part that quietly breaks it is forgetting to authorise the agent for every tax that matters — a 64-8 only covers the taxes you tick, so an estate ticked for Inheritance Tax alone leaves the deceased's income tax beyond the agent's reach.
The mistake that leaves your agent locked out
Authorising the agent for too few taxes.
A 64-8 covers an agent only for the taxes you tick on the form.
If you appoint a solicitor to handle estate administration and tick only 'Inheritance Tax', they cannot discuss the deceased's outstanding income tax or Self Assessment return with HMRC — you would need a separate 64-8 (or an amended one) for those taxes.
Executors are often surprised to find they must deal with HMRC's income tax correspondence themselves because the agent's 64-8 was drawn too narrowly.
For most estates, tick both Self Assessment and Inheritance Tax, and add PAYE if the deceased was employed.
Form 64-8 is the official authorisation that allows a tax agent (solicitor, accountant, tax adviser, or other professional) to deal with HMRC on behalf of the taxpayer — or, in an estate context, on behalf of the personal representatives.
Without a valid 64-8, HMRC will refuse to discuss the deceased's or the estate's tax affairs with any third party, including the deceased's own solicitor.
A 64-8 authorises an agent for specific taxes (which the executor must specify) and remains in force until revoked.
·Who Files — The personal representative(s) — executor(s) or administrator(s) — acting on behalf of the estate. Each executor must sign.
·2 pages · 12 fields guided
·Draws from your Estate File — People, Authority & Contacts, Personal Record
Section01
§11
Section 1
What the 64-8 authorises — and what it does not
A 64-8 is a broad authorisation that allows the agent to correspond with HMRC, receive copies of notices and correspondence, and discuss the client's tax affairs.
It does not give the agent power to sign legal documents on the estate's behalf or make binding decisions.
01
What the agent can do with a 64-8
Receive copies of HMRC correspondence (letters, assessments, demands).
Telephone HMRC on behalf of the estate.
Submit tax returns and accounts.
Receive repayments (subject to HMRC's rules).
Correspond with HMRC about enquiries, disputes, or appeals.
02
What requires separate authority
Signing legal documents (deeds, declarations) requires a power of attorney, not a 64-8.
Receiving repayment cheques directly requires specific payment authority.
The 64-8 is purely about HMRC communication authorisation — it does not make the agent a signatory on bank accounts or give them any authority outside HMRC matters.
03
Online agent authorisation vs 64-8
HMRC has an online system ('agent authorisation') for agents to be authorised for individual taxpayers with a Government Gateway account.
However, for estates (which typically do not have a Government Gateway account), the paper 64-8 is still required.
Some accountancy firms will handle this online route for individuals but use the paper 64-8 for estate matters — either route is valid if correctly completed.
A 64-8 is a broad authorisation that allows the agent to correspond with HMRC, receive copies of notices and correspondence, and discuss the client's tax affairs.
HM Revenue & Customs (HMRC) · 64-8❦
Section02
§22
Section 2
Completing the 64-8
The 64-8 is a short two-page form. For estate purposes, you are completing it on behalf of the deceased's estate rather than on behalf of yourself personally.
01
Section 1 — the taxpayer details
For an estate: full name of the deceased, their date of birth, their National Insurance number, and their Unique Taxpayer Reference (UTR) if they were registered for Self Assessment.
If you are also authorising the agent for the estate's own tax position (as opposed to the deceased's pre-death affairs), you may also need an estate UTR — HMRC will provide one when they are notified of the death.
02
Section 2 — the agent details
The agent's name, address, their firm's name, and their HMRC agent code (the 6-character code HMRC issues to registered agents).
The agent will provide their agent code — it is not something you look up yourself.
If you do not have it, ask the agent before completing the form.
03
Section 3 — which taxes to authorise
Tick all relevant boxes: Self Assessment (for the deceased's outstanding income tax return); Inheritance Tax (for the IHT400 and HMRC correspondence about the estate); PAYE (if the deceased was employed or had a PAYE code); Corporation Tax (if relevant); VAT (if the deceased ran a VAT-registered business).
For most estates, Self Assessment and Inheritance Tax are the relevant ones.
Be specific — HMRC will not assume the agent is authorised for taxes you did not tick.
04
Multiple executors — all must sign
If there are two or more executors, all of them must sign the 64-8 for it to be valid.
HMRC will return a 64-8 that is signed by only one of several named executors.
Allow time for all executors to sign — if they are in different locations, the form may need to be posted between them.
05
Where to send it
Send to HMRC, PAYE and Self Assessment, BX9 1AS (the general inbox) or, for Inheritance Tax specifically, to HMRC Inheritance Tax, Ferrers House, PO Box 38, Castle Meadow Road, Nottingham, NG2 1BB.
Your agent may prefer to submit it on your behalf — confirm with them which route to use.
The 64-8 is a short two-page form. For estate purposes, you are completing it on behalf of the deceased's estate rather than on behalf of yourself personally.
HM Revenue & Customs (HMRC) · 64-8❦
Many people file 64-8 themselves — that is what this walkthrough is for. If the estate behind it has stopped being simple — inheritance tax to pay, a trust, foreign assets, a dispute — Signum, Valoren’s own specialist desk, can take it on, and we say so plainly: it starts with a free intake, and if you do not need us, we will tell you. Prefer an independent adviser? STEP and the Chartered Institute of Taxation both keep public member directories, and neither pays Valoren a referral fee.
FAQ
64-8 questions, answered.
Form 64-8 is HMRC's official authorisation that lets a tax agent — a solicitor, accountant, or tax adviser — deal with HMRC on the estate's behalf (Taxes Management Act 1970 s.3A).
Without a valid 64-8, HMRC will not discuss the deceased's or the estate's tax affairs with any third party, including the deceased's own solicitor.
It covers correspondence only; it does not give the agent power to sign legal documents or access bank accounts.
The personal representatives — the executor(s) named in the will, or the administrator(s) if there is no will.
You complete it on behalf of the deceased's estate rather than for yourself personally, naming the agent you have instructed.
If there is more than one executor, every one of them must sign.
There is no fixed statutory deadline.
In practice you complete it as soon as you instruct a professional, because until it is signed and accepted the agent cannot act — HMRC will not speak to them about the estate.
A 64-8 stays in force until it is revoked, so there is no renewal date to track.
No.
Form 64-8 is free to complete and submit to HMRC.
The only costs involved are the professional fees of the agent you are authorising, which are separate from the form itself.
For the taxpayer details you need the deceased's full name, date of birth, National Insurance number, and their Unique Taxpayer Reference (UTR) if they were registered for Self Assessment — plus any estate UTR HMRC issues once the death is notified.
For the agent details you need the agent's name, firm, address, and 6-character HMRC agent code, which the agent supplies.
You also need the signatures of all executors or administrators.
Authorising the agent for too few taxes.
A 64-8 only covers the taxes you tick — so if you appoint a solicitor and tick only 'Inheritance Tax', they cannot discuss the deceased's outstanding income tax or Self Assessment return with HMRC.
For most estates you will want to tick both Self Assessment and Inheritance Tax (and PAYE if the deceased was employed).
Forgetting a tax means a second 64-8 later, and HMRC will not assume authority you did not grant.
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Where this fits
64-8 is one form. The file behind it is the rest.
Forms are easier when the records are ready.
For form 64-8, that means the deceased's National Insurance number and Unique Taxpayer Reference, any estate UTR HMRC has issued, the appointed agent's name and 6-character HMRC agent code, and the full names and signatures of every executor or administrator.
When you're ready — not before — our £179 Executor's First Hour walks you through registering the death, notifying banks and pensions, and getting probate started, in the right order. The free checklist above covers the essentials; this is for when you'd rather have a hand to hold. Executor's First Hour — £179 →
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