From 18 May 2026, HMRC is introducing a new requirement for businesses that interact with HMRC on behalf of clients to register as a tax adviser.
For many law firms, this may apply even if tax advice is not a core service. If your firm deals with HMRC as part of client work, it is important to understand whether you fall within scope and what you need to do next.
What is changing?
HMRC is launching a new registration system for agents who handle tax matters for clients.
In simple terms, if your firm communicates with HMRC about a client’s tax affairs and is paid for doing so, you may need to register. This includes submitting returns, claims or other information to HMRC on a client’s behalf.
Why this matters for conveyancing teams
This is particularly relevant for law firms with property or conveyancing departments.
Even where tax is not your primary focus, filing Stamp Duty Land Tax (SDLT) returns for clients can bring your firm within scope. In practice, this means many firms that would not typically describe themselves as tax advisers may still need to register.
Who needs to register?
The requirement applies to the legal entity, not individual employees.
However, HMRC will carry out checks on certain people within the firm, known as relevant individuals. This usually includes directors or partners, individuals involved in tax-related work, and those responsible for overseeing or managing that work.
The exact number of people assessed depends on the size and structure of the firm, but most firms will need to nominate at least five individuals if they have a larger leadership team.
What are the conditions?
To register, your firm must meet a number of HMRC conditions.
These include being supervised for anti-money laundering, typically through your professional body, being up to date with tax filings and payments, having no relevant fraud or tax-related convictions, and not being subject to insolvency or disqualification issues.
These checks will also apply to the relevant individuals within your firm.
When do you need to act?
The timeline depends on your current setup.
18 May 2026
Registration opens for firms without an Agent Services Account
18 August 2026
Firms with existing Self Assessment or Corporation Tax agent accounts
18 November 2026
Firms providing third-party payroll services
31 December 2026
Financial services firms
Once your deadline applies, you will have three months to complete your registration. During this period, you can continue to deal with HMRC while your application is being processed.
What happens if you do not register?
If your firm is required to register and does not do so, you may no longer be able to interact with HMRC on behalf of clients.
This could lead to delays in completing work, particularly in areas such as conveyancing where SDLT submissions are time sensitive. HMRC also has the power to issue penalties or prevent firms from acting if the rules are not followed.
What should law firms do now?
Now is the time to review your position.
You should consider whether your firm interacts with HMRC on behalf of clients, whether you submit SDLT returns as part of your services, who within your firm may be classed as a relevant individual, and whether your compliance processes and AML supervision are up to date.
Taking a proactive approach now will help avoid disruption later.
How SMH Group can help
At SMH Group we work closely with law firms, supporting them with tax compliance, advisory services and regulatory changes.
If you are unsure whether these new rules apply to your firm, or you would like support with registration and ongoing compliance, our team is here to help.
Get in touch with us on 0330 1070 873 or email stampduty@smh.group to discuss your requirements.
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