HMRC's Tax Adviser Registration: Why Property Buyers, Sellers and Investors Should Pay Attention

If you buy, sell or develop property in England or Northern Ireland, there's a regulatory change coming this spring that could affect your next transaction — and not in the way the government intends.

From 18 May 2026, anyone who interacts with HMRC on behalf of a client's tax affairs must be registered with HMRC under a new mandatory regime introduced by Part 7 of the Finance Bill 2025-26. That includes solicitors, licensed conveyancers and property lawyers who submit Stamp Duty Land Tax returns — which is virtually every conveyancing firm in the country.

HMRC published its guidance on 17 February 2026 and confirmed what the profession feared: there is no exemption for conveyancers. If you file SDLT returns for clients and get paid for it, you are a tax adviser in HMRC's eyes — whether or not you describe yourself that way, whether or not it's your main business, and even if you only do it for one client.

What's actually happening?

The new regime, set out in clauses 220 to 250 and Schedule 19 of the Finance Bill, requires all "tax advisers" — defined broadly as anyone who, in the course of business, assists others with their tax affairs — to register for an HMRC Agent Services Account before interacting with HMRC on behalf of clients. Registration will be phased: most firms must register from 18 May 2026, with those already holding Self Assessment or Corporation Tax agent accounts given until 18 August 2026. Third-party payroll-only providers have until November.

The registration conditions are not trivial. Firms and their senior managers must satisfy "fit and proper" requirements, including being up to date with their own tax affairs, having no outstanding anti-avoidance penalties, and meeting professional standards that HMRC has yet to fully define. The ICAEW has warned that the eligibility conditions for every senior manager could be problematic for larger firms, where one partner's personal tax compliance could jeopardise the entire organisation's registration.

Firms that fail to register face being barred from interacting with HMRC on behalf of clients. Continued interaction after a compliance notice could result in financial penalties and a temporary or permanent ban from registration.

Why the profession is pushing back

The objections have been loud and united. The Law Society called the legislation "unfair and unwieldy." The Council for Licensed Conveyancers wrote directly to the Chief Secretary to the Treasury warning of duplicated regulation and perverse outcomes. The Association of Taxation Technicians recommended delaying mandatory registration until April 2027 at the earliest, given that key operational details remain unpublished. The ICAEW went further, describing the measures as posing an "existential threat" to advisers and calling for significant amendments.

A central criticism is that the regime captures the wrong people. Conveyancers and property solicitors don't give tax advice — they submit SDLT returns as agents, acting on their clients' instructions. As Dame Janet Paraskeva of the CLC pointed out, requiring them to register as tax advisers creates the misleading impression that they are authorised to advise on tax, which they are not. That, she argued, actually increases the risk of wrongdoing by giving bad actors a veneer of HMRC-endorsed legitimacy.

Tax commentator Dan Neidle, formerly of Clifford Chance, made a sharper point: those who genuinely peddle harmful avoidance schemes typically don't submit returns themselves, so they won't be captured by a regime that only targets those who interact directly with HMRC.

What this means in practice for property transactions

Here's where it gets real for clients:

• Timing risk around launch. If a firm isn't registered by the time it needs to submit your SDLT return, it simply can't do so. SDLT must be filed within 14 days of completion — miss that, and penalties and interest start accruing. Any bottleneck in HMRC's registration system around May or August 2026 could create real problems for transactions completing in that window.

• Increased compliance costs. Every conveyancing firm will need to register, maintain compliance, ensure its senior personnel pass HMRC's checks, and manage a parallel regulatory obligation alongside SRA or CLC regulation. That overhead will be priced into fees. It may be modest per transaction, but it compounds across portfolios — and it hits sole practitioners and smaller firms disproportionately hard.

• More administration per file. Firms will need to evidence and maintain their registration status, potentially provide registration details to clients or lenders, and manage the risk of suspension if HMRC considers their conduct falls below expected standards — standards that, at the time of writing, have still not been fully published.

• A shrinking pool of providers. The conveyancing sector is already under pressure. Research published this month shows the number of registered conveyancers in England and Wales has fallen from over 4,000 in 2022 to just 3,425 in January 2026, while practising solicitors in residential conveyancing have dropped by over 2,000 since 2021. Adding another regulatory burden to an already stretched profession risks accelerating that decline — at exactly the point where transaction volumes are growing again.

The irony isn't lost on us

The government's own consultation on home buying and selling reform, published in October 2025, acknowledged that the conveyancing process now takes 60% longer than it did in 2007 and committed to streamlining it. Introducing a new registration regime that adds cost, complexity and potential delay to every residential transaction sits uncomfortably alongside that ambition.

Nobody disputes the value of raising standards in the tax advice market. But a regime that sweeps in thousands of property lawyers and conveyancers — professionals already subject to robust regulatory oversight — while leaving the genuine bad actors untouched, deserves serious scrutiny.

If you're completing a property transaction in the second half of 2026, ask your solicitor whether they're on top of this. And if you're a developer or investor running multiple deals, factor in the possibility of modest fee increases and transition-period friction.

This is one to watch.