HMRC is bringing in mandatory registration for tax advisers. If someone else files your Self Assessment or corporation tax return for you, such as a bookkeeper or adviser, it’s worth checking whether this affects them.
The second registration window runs from 18 August to 17 November 2026. Advisers who have a Self Assessment or corporation tax agent account but no Agent Services Account need to apply by Tuesday 17 November 2026. The ban on acting while unregistered applies to them from 18 November 2026.
Advisers who apply within their window can keep acting while HMRC processes the application.
Key points
- Phase 2 of mandatory tax adviser registration runs from 18 August to 17 November 2026.
- Advisers with a Self Assessment or corporation tax agent account but no Agent Services Account need to apply by Tuesday 17 November 2026 (HMRC describes this as registering by 18 November).
- Payroll-only advisers don’t need to register before 18 November. Financial services organisations don’t need to register before 31 December 2026. Existing Agent Services Account holders don’t re-register.
- Advisers must have approved anti-money-laundering supervision before applying.
- Advisers who don’t register when required may have their ability to act limited and may face penalties.
On this page
What’s changing
HMRC is requiring tax advisers to register with it. Phase 2 of mandatory tax adviser registration runs from 18 August to 17 November 2026 (HMRC manual MTAR10800).
This is a rule for advisers, not for you as a taxpayer. But if the person who files your returns is caught by it and doesn’t register, it could affect you.
Who needs to register now
Advisers who have a Self Assessment or corporation tax agent account but no Agent Services Account need to apply by Tuesday 17 November 2026. The ban on acting while unregistered applies to them from 18 November 2026 (SI 2026/807).
HMRC’s guidance helps advisers work this out: Check if and when you need to register as a tax adviser with HMRC.
Who doesn’t need to register yet
- Payroll-only advisers don’t need to register before 18 November.
- Financial services organisations don’t need to register before 31 December 2026.
- Existing Agent Services Account holders don’t re-register. HMRC will migrate them by 31 March 2027.
Anti-money-laundering supervision comes first
The adviser’s business must have approved anti-money-laundering (AML) supervision before it applies. HMRC will reject applications made without it. HMRC sets out the conditions here: Check if you meet HMRC’s conditions to register as a tax adviser.
Why it matters to you
Advisers who don’t register when required may have their ability to act limited and may face penalties. That could affect who can deal with HMRC on your behalf.
If someone other than us files your Self Assessment or corporation tax returns, it’s reasonable to ask them:
- Do you have an Agent Services Account?
- If not, have you applied to register with HMRC, or will you by 17 November 2026?
- Do you have approved anti-money-laundering supervision?
If you run a small practice
If you’re a small practice that refers work to us, HMRC’s guidance and manual set out the detail, including MTAR10800 in HMRC’s Mandatory Tax Adviser Registration manual. Please check the rules for your own business against the GOV.UK pages linked below.
Sources
Our main sources are HMRC and GOV.UK:
- HMRC news: second registration window now open for tax advisers
- Check if and when you need to register as a tax adviser with HMRC
- Check if you meet HMRC’s conditions to register as a tax adviser
- HMRC manual: Mandatory Tax Adviser Registration (MTAR10800)
- The Finance Act 2026 (Registration of Tax Advisers) (Appointed Days and Transitional Provision) Regulations 2026 (SI 2026/807), legislation.gov.uk
Talk to us
If you’re not sure how this affects the person who files your returns, or you have questions about the rules, get in touch. Call us on 020 7164 0225, send us a WhatsApp message or email your tax enquiry to hello@ibandco.co.uk.
See also our Business Tax Advisory and Personal Tax Planning services.
Checked on 9 October 2026. The Budget on 28 October 2026 may change some of these rules and rates. We plan to review this post after the Budget. Please check with us before acting.
Please note: this article is general information based on our understanding of UK tax rules at the date shown above. It is not advice for your circumstances, and tax rules and rates can change. Please speak to us before acting on it.
Ishmael Bangura FFA
Ishmael Bangura FFA is a qualified tax adviser and Fellow Financial Accountant with a finance degree and 15 years’ experience across corporate finance and practice, including earlier corporate roles. He and his team have helped more than 950 clients. IB&Co Accountants is regulated by the IFA and IPA. IB&Co is based at Level 37, 1 Canada Square, Canary Wharf.
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