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HMRC email warning to sign up to tax advisers register
- Sara White
- Aug 19
- 2 min read
Accountants not yet signed up to mandatory tax adviser register are being sent emails by HMRC to warn must sign up before final deadline.
The new HMRC tax adviser register is mandatory and requires any tax agent and accountancy firms to sign up to the new system ‘if they interact with HMRC’.
The emails will be sent to firms and sole practitioners with and without an agent services account (ASA), clarifying that any organisation without an ASA will have to open one to continue ‘interacting’ with the tax office.
HMRC started sending the emails out on 5 August and will continue through to 17 November 2026.
In a notice confirming the email campaign, HMRC stated: ‘You may receive an email if you’re a tax adviser. The email will confirm that the mandatory tax adviser registration window for agent services accounts is open from 18 August 2026 to 18 November 2026, and will:
ask you to check whether you are already registered for an agent services account; and
provide you with instructions if you need to register for an agent services account
let you know what will happen if you do not have an agent services account before 18 November 2026.
The register is mandatory with severe penalties for failing to register and non-compliance will hamper firms’ ability to work with HMRC.
The requirements are complicated with various sign up rules and beyond tax advisers captures payroll professionals and conveyancers. This campaign is particularly targeting tax agents and advisers as other sectors have later sign-up deadlines.
The HMRC register does not apply to tax managers working for in-house tax teams in companies and corporations.
HMRC has an online tool at gov.uk to check whether a business, firm or sole practitioner needs to register under the new rules of eligibility on interaction. This is a good starting point if there is any confusion about whether a firm must register.
However, the online checker comes with a caveat as when testing the system, the result is accompanied by an advisory message from HMRC, which states: ‘This is based on the information you have provided. The results do not provide a formal decision by HMRC’. Reminders of the CEST tool for IR35 so caution is required.
In terms of deadlines, income tax self-assessment or corporation tax accounts started on 6 August 2026, and third party payroll providers will have to register from November 2026.
All the professional bodies including ICAEW, CIOT, ICAS, ACCA, ATT, AAT and Chartered Accountants Ireland have detailed support for members about how to register.
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Deadlines for HMRC tax adviser register from 18 May | 18 May 2026
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