Advice for advisers

In my work advising law firms on their financial and compliance affairs, regulatory change is a familiar topic. But over the past few months, one issue has come up more than any other, and often catches solicitors off guard: Are you prepared to register your firm as an agent with HM Revenue & Customs (HMRC)? And in a surprising number of cases, the answer is no. 

From May 2026, HMRC will introduce a mandatory registration requirement for tax advisers. And the definition of ‘tax adviser’ is far wider than many solicitors expect. If your firm submits stamp duty land tax (SDLT) returns, handles probate and inheritance tax forms or corresponds with HMRC about a client’s tax position in any way, these rules almost certainly apply.

This article sets out, in practical terms, who needs to register, what the process involves, who is exempt and what your firm should be doing now.

What’s prompted this change?

HMRC has long expressed concern about inconsistent standards in the tax advice market. The new rules, via the statutory registration gateway, are designed to give HMRC a clearer view of who is acting for taxpayers and to ensure that anyone who interacts with HMRC on a client’s behalf meets defined minimum standards.

The new system opens on 18 May 2026. Firms will be phased in, with each group given a three-month window to register once they are brought into scope. After these transition periods, HMRC intends that only registered advisers will be able to interact with HMRC on behalf of clients.

For law firms, this is less about tax policy and more about protecting your ability to carry out everyday work – from completing a conveyance to administering an estate. 

Who needs to register?

HMRC’s February 2026 guidance is straightforward: If your business interacts with HMRC about someone else’s tax affairs and you are paid for that work, you must register.

It doesn’t matter whether you call it ‘tax advice’ or not. It doesn’t matter whether it’s a small part of a wider legal service. If you’re sending information to HMRC on a client’s behalf, you’re in scope.

In practice, this captures:

• probate and client teams filing inheritance tax (IHT) forms or corresponding about estates
• conveyancers submitting SDLT returns
• trust practitioners dealing with trust tax positions, and
• any fee-earning team sending tax-related documents to HMRC as part of their work.

Professional bodies asked HMRC to exempt legal professionals who submit tax forms only as part of a broader legal process, but HMRC declined.

Who does not need to register?

The list of exemptions is short. The most relevant are:

• Work done entirely free of charge, such as pro bono.
• Acting for a client in a court or tribunal appeal, but this exemption applies only to the appeal work. If the firm also deals with HMRC on the client’s wider tax affairs, registration is still required.

Other exemptions – such as in-house tax teams, group-only tax work, certain insolvency practitioners and software providers – are unlikely to apply to most law firms.

Registration at firm level and who HMRC will check

Registration happens at firm level, not individual solicitor level. Fee earners don’t register personally, which will come as a relief to many teams.

However, HMRC will still look closely at certain people within the firm – the ‘relevant individuals’. These are the partners, directors, limited liability partnership (LLP) members and senior employees who play a significant role in managing or organising the firm’s tax-related work.

Broadly, smaller firms with five officers or fewer will need to name all officers and any employee who plays a significant role in managing tax-related work. Larger firms with six or more officers must name all individuals (officers or employees) who significantly manage or organise tax adviser activities, with at least five officers named in total. Professional bodies have noted that HMRC’s guidance here is still evolving, so firms should expect further clarification.

One important point: if a relevant individual fails HMRC’s conditions, the firm’s entire registration is at risk. The Chartered Institute of Tax has highlighted this as a key concern and recommends reviewing partnership and director agreements to ensure the firm can act if issues arise.

This summary is based on HMRC guidance and professional commentary as at April 2026 and may be updated as further detail emerges. 

When you need to register

Registration opened on 18 May 2026 and there’s no fee for registration.

HMRC is phasing firms into the regime, so your registration window depends on your current HMRC setup:

• No agent services account (ASA): register from 18 May 2026.
• Self assessment or corporation tax online account but no ASA: register from 18 August 2026.
• Already have an ASA: re-registration is not required; HMRC will contact you for additional information.

Each group has a three-month window to complete registration once brought into scope.

What your firm should do now

The firms that will glide through this process are the ones which take a little time now to get organised. None of the preparation is difficult but it’s far easier to do it before the registration window opens.

Understand how your firm interacts with HMRC

Start by mapping where HMRC interaction happens across your firm. For many practices, this sits in probate, conveyancing, trusts and general private client work. Knowing where the touchpoints are helps you identify which teams are affected.

Check your ASA

Some firms have an ASA and rarely use it; others don’t realise they have more than one. It’s worth confirming what your firm actually has in place.

The simplest way to check this is to try signing in via GOV.UK using the Government Gateway credentials your firm normally uses for SDLT, IHT or other tax submissions. If the login takes you to an ASA dashboard, you have one. If it doesn’t, or if no one is sure which credentials are current, that’s a sign to tidy things up now, because your registration date depends on your existing setup.

It’s also worth checking who has access and whether the contact details linked to the account are still correct. Many firms discover their ASA is tied to an old email address or a former employee, which slows things down later.

Gather the information HMRC will ask for

When you register, HMRC will ask for a set of firm-level details. None of it is complicated, but it’s the sort of information that can take time to track down if you leave it until the last minute.

Firms will need their:

• unique taxpayer reference – this is the 10-digit number HMRC uses to identify your business for tax purposes
• postcode
• Companies House number (if applicable)
• VAT details, and
• anti-money laundering (AML) supervisory body information.

Sole practitioners and partnerships will need their national insurance (NI) numbers and dates of birth for identity checks.

Brief your teams

Make sure the people who submit SDLT returns, file IHT forms or correspond with HMRC understand that registration is coming and know what will change. A short internal briefing now can prevent confusion later.

What HMRC will check and identifying your relevant individuals

When you register, HMRC will assess both the firm and its relevant individuals against a set of eligibility conditions. These are not onerous but they are specific, so are worth checking early.

The firm must be up to date with its tax filings and have no outstanding liabilities unless covered by an agreed payment plan. HMRC will also look for any history of anti-avoidance sanctions, stop notices or unspent convictions for fraud or tax offences. Insolvency, a previous decision by HMRC refusing to deal with the firm, or being suspended or banned from registering will also prevent approval.

The firm must also be properly supervised for AML. Relevant individuals don’t need to provide AML evidence personally, but they must not be disqualified from acting as a director, whether in the UK or overseas.

Most firms will meet these conditions without difficulty, but it’s still sensible to check early and to ensure your governance documents allow the firm to act if a relevant individual becomes a problem.

Is there an issue if you don’t declare every relevant individual?

HMRC has not stated that there will be a grace period for failing to declare all relevant individuals; the three-month window allows firms time to liaise with HMRC where needed. However, because the definition is unclear and HMRC has not yet published enforcement detail, professional bodies expect HMRC to take a proportionate approach early on. For all questions about who does and does not qualify as a relevant individual, it’s advised to engage with HMRC once the registration period begins.

What happens if a relevant individual or the firm fails HMRC’s checks?

If a firm or any named relevant individual fails HMRC’s checks, HMRC has the power to refuse, suspend or remove the firm’s registration, which in practice could stop the business from interacting with HMRC on behalf of its clients. 

Professional bodies expect sanctions to apply where firms don’t meet the new conditions, although the full detail will sit in secondary legislation. In these cases, firms should remove or replace the individual who failed the checks, update HMRC with the revised information, review their governance to ensure remaining individuals meet the standards and engage with HMRC if they believe its decision is incorrect, as a right of review and appeal will be available.

What happens if you don’t register?

If a firm required to register fails to do so and continues interacting with HMRC, HMRC can issue a compliance notice. Continued interaction can lead to financial penalties. In serious cases, the firm can be permanently banned from registering.

A firm that cannot register cannot submit SDLT returns, probate tax forms or deal with HMRC on any client matter.

Are there any ongoing commitments post-registration?

Yes, there will be ongoing obligations, but HMRC has not yet published the full details. What we do know is that firms must continue to meet the ‘minimum standards’, must maintain accurate information about relevant individuals and must report any changes in key staff.

Conclusion

HMRC’s new registration requirement is a meaningful shift for law firms, but it’s entirely manageable with early preparation. The key is to understand whether you are in scope, know your registration date, gather the required information and ensure your ASA and governance are in order.

The earlier you prepare, the smoother the process will be.