New SDLT Registration Rules (From May 2026): What law firms and other professional advisers need to know
Stamp Duty Land Tax (SDLT) mandatory tax registration is coming into force in May 2026 and will affect professionals who interact with HM Revenue & Customs (HMRC) on behalf of clients in relation to tax matters. For many law firms and conveyancers, this includes submitting SDLT returns as part of property transactions.
Under the new rules, advisers who interact with HMRC on behalf of clients will be legally required to register and meet minimum standards before doing so. While the change is aimed at raising standards across the tax advice market, it also introduces new responsibilities for firms involved in property transactions.
For some practices this will mean reviewing internal processes and registering with HMRC. For others, it may be a prompt to reconsider how SDLT submissions are handled.
27th April 2026
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Laura Wylie See profile
What are the new SDLT registration rules?
HMRC is introducing a mandatory registration system for tax advisers as part of upcoming legislation expected to take effect from May 2026.
The key point is straightforward. If a professional interacts with HMRC on behalf of a client in relation to tax matters, they must first register with HMRC and meet the required standards. This includes submitting SDLT returns.
Once the system opens, advisers will need to complete a digital registration process. Firms will then have a transition period of at least three months to register and adapt their processes.
Historically, submitting an SDLT return has often been treated as an administrative step within a property transaction. Under the new regime it will be recognised as a tax activity. As a result, the individuals or firms carrying out this work must meet HMRC’s minimum standards for tax advisers.
What this means for conveyancers and law firms
For many law firms, SDLT filings sit alongside conveyancing work rather than forming part of a dedicated tax advisory service. The new rules introduce additional compliance considerations for those continuing to submit returns directly.
Firms will need to decide how they want to approach SDLT work in the future. Some may choose to complete the registration process and manage the compliance requirements internally. Others may decide that working with a specialist tax adviser provides a more efficient and lower-risk approach.
This decision will often come down to resources, internal expertise and the complexity of the transactions being handled.
SDLT can become particularly technical when transactions involve mixed-use property, multiple dwellings, corporate purchasers, development structures or claims for reliefs. In these cases specialist tax input can provide reassurance that calculations and submissions are handled correctly.
How Old Mill can help
Old Mill’s SDLT Team regularly supports law firms and professional advisers nationwide with SDLT advice, calculations and submissions, including complex property transactions. Our role is to help ensure returns are accurate, compliant and submitted correctly to HMRC.
Working with a specialist team allows firms to maintain focus on their core legal work while accessing technical tax expertise when it is needed.
We support firms across a range of SDLT matters, from straightforward submissions to more complex transactions involving reliefs, restructuring or property development.
'Dealing with SDLT in increasingly difficult. We work closely with Laura and her team to navigate through potential SDLT risks and reliefs available. From advising on what further information might be needed (with reference to the latest cases and Revenue decisions) to the likelihood of a relief being successfully claimed. The advice is always clear and delivered on time which is a huge benefit to us and our clients.'
Alison Treble – Residential Property Partner, Mogers Drewett
Speak to our SDLT specialists
The new SDLT registration requirements introduce an additional layer of compliance for firms interacting with HMRC. For many practices, working with specialist advisers will provide a practical way to manage that responsibility.
If you would like to discuss how the upcoming changes may affect your firm, or explore how Old Mill can support your SDLT submissions, please contact Laura Wylie, Associate Director who will be happy to help.
