Key takeaways
- HMRC says a trustee does not need to register as a tax adviser just because they file trust returns, pay the trust's tax or deal with HMRC as trustee.
- The trustee exemption covers individual and corporate trustees, and employees of a corporate trustee acting in that role.
- A firm paid to provide tax services to trustees under a separate commercial arrangement is not automatically covered and may need to register.
- HMRC's registration guidance and manual do not mention executors or personal representatives; the general test of being paid to deal with HMRC about someone else's tax applies.
- Advisers with Self Assessment or Corporation Tax agent accounts but no agent services account must register by 18 November 2026.
- An unregistered adviser under a compliance notice faces a penalty of £5,000 per prohibited interaction, rising to £10,000 in some cases.
Trustees who deal with HMRC only in their role as trustee do not need to register as tax advisers. HMRC’s manual says filing trust returns, paying the trust’s tax and talking to HMRC about the trust is handling the trust’s own affairs, not advising a client. The position for executors is less clear: HMRC has not addressed them directly, so paid professional executors should apply the general test before the 18 November 2026 deadline.
What does HMRC say about trustees?
HMRC says a trustee will not have to register merely because they act as trustee. Its Mandatory Tax Adviser Registration manual at MTAR10200 lists the activities covered:
- preparing or filing the trust’s tax returns
- arranging payment of the trust’s tax
- giving tax input about the trust
- dealing with HMRC about the trust’s tax affairs
HMRC treats this as the trust’s own tax affairs. The same rule applies to individual trustees and to companies acting as corporate trustee. An employee who deals with HMRC for a corporate trustee does not register personally because of that contact.
Where there are several trustees, one can act as lead trustee with HMRC. The others stay responsible for the trust’s tax, as GOV.UK’s guide to trustees’ tax responsibilities explains.
When does trust work need registration?
Registration is needed when someone outside the trustee role is paid to deal with HMRC about the trust. HMRC says the trustee treatment “does not extend automatically” to a separate person or firm providing tax services to the trustees or the trust under an independent commercial arrangement.
That covers the common practice case. If your firm prepares the SA900 trust and estate return for lay trustees and files it as their agent for a fee, you are acting as a tax adviser to those trustees.
HMRC also warns about corporate groups. Being in the same group as a corporate trustee does not automatically bring a firm within the group exemption in paragraph 1(1)(f) of Schedule 20 to the Finance Act 2026. Each arrangement turns on its facts.
Where do executors stand?
HMRC’s guidance does not mention executors or personal representatives. We checked the registration guidance on GOV.UK and the MTAR manual pages on scope (MTAR10100), groups and trusts (MTAR10200) and exceptions (MTAR10300). None of them addresses estates.
The general test therefore applies. Under MTAR10100, a tax adviser is someone who, in the course of a business and for payment, helps others with their tax affairs and interacts with HMRC for them. Non-cash benefits count as payment.
The Solicitors Regulation Authority has told firms they are likely to need to register if they manage a client’s tax affairs, for example as an executor or under a deputyship. That is the regulator’s view, not HMRC’s.
Which applies to you?
| Your situation | Register? |
|---|---|
| Lay trustee dealing with HMRC for the trust | No, on HMRC’s guidance |
| Corporate trustee acting as trustee | No, on HMRC’s guidance |
| Firm paid to file returns for trustees | Yes |
| Unpaid family executor | Unlikely; unpaid help for family is out of scope |
| Paid professional executor | Likely; HMRC has not confirmed |
If a firm does any in-scope work as well, it must register. HMRC says exceptions apply activity by activity, and a business cannot use one to avoid registering for the rest.
What are the deadlines?
The deadline depends on which agent accounts your firm holds. HMRC set these windows in its 18 August 2026 announcement:
| Group | Window |
|---|---|
| No agent account at all | Closed 18 August 2026; register now |
| Self Assessment or Corporation Tax account, no ASA | 18 August to 18 November 2026 |
| Payroll-only providers | 18 November 2026 to 18 February 2027 |
| Financial services organisations | 31 December 2026 to 31 March 2027 |
Firms that already hold an agent services account (ASA) do not register again. HMRC says they will move to the new service by 31 March 2027. Registration is free and you apply online through the agent services account.
What if you should register and do not?
HMRC can restrict your dealings and charge penalties. Under MTAR30400, an adviser under a compliance notice pays £5,000 for each prohibited interaction. That rises to £10,000 after four or more £5,000 penalties in two years, or under an ineligibility order. HMRC must give 30 days to make representations, and a reasonable excuse defence applies.
What advisers should do now
- List every trust and estate client and who files their returns.
- Separate trustee work from agent work. Note where the firm, not a trustee, deals with HMRC for a fee.
- Check your agent accounts. If you hold Self Assessment access without an ASA, register by 18 November 2026.
- Record your reasoning for executor work. HMRC has not ruled on it, so keep a file note.
- Check you meet HMRC’s conditions, including AML supervision. See AML registration for accountants.
For the wider rules, see our posts on the 18 November deadline and HMRC’s standard for agents. Our IHT reporting and probate guide covers the estate returns themselves.
Frequently asked questions
Do trustees need to register as tax advisers with HMRC?
No, if they deal with HMRC only as trustees. HMRC’s manual at MTAR10200 says filing and paying the trust’s tax does not require registration.
Does an accountant who prepares trust returns need to register?
Yes, if they are paid and deal with HMRC for the trustees. HMRC says the trustee exemption does not automatically cover a separate firm under a commercial arrangement.
Do executors need to register as tax advisers?
HMRC has not said. An unpaid family executor is unlikely to be in scope, while the SRA says professional executors are likely to need to register.
Is a corporate trustee exempt?
A corporate trustee acting as trustee is treated like an individual trustee. Other companies in its group need to check their own position.
When is the deadline for tax adviser registration?
18 November 2026 for advisers with Self Assessment or Corporation Tax agent accounts but no agent services account.
Sources
Rates, thresholds and rules in this guide were checked against HMRC and GOV.UK guidance on 6 November 2026. Tax rules change, so check the current position on GOV.UK or with a qualified adviser before acting. This guide is general information, not personal advice.
- MTAR10200: groups and complex business structures, including trusts (HMRC manual)
- MTAR10100: who must register as a tax adviser (HMRC manual)
- Check if and when you need to register as a tax adviser with HMRC (HMRC, updated 3 September 2026)
- Second registration window now open for tax advisers (HMRC, 18 August 2026)
- MTAR30400: financial penalties for prohibited interactions (HMRC manual)
- Trustees' tax responsibilities (GOV.UK)