If your accounting firm holds an existing Self Assessment or Corporation Tax agent code and you have not yet registered under HMRC's new mandatory Tax Adviser Registration (TAR) scheme, you have until the 18th of August 2026 to do so. That is three days from today.
This is not a soft nudge. Firms that fail to register and continue attempting to interact with HMRC on behalf of clients face formal sanctions, including the loss of the ability to act for those clients. For most practices, that is an existential risk.
Introduced under Part 7 of the Finance Act 2026, mandatory Tax Adviser Registration is the first statutory registration requirement ever to apply to the UK tax advice sector as a whole. From the 18th of May 2026, any firm that interacts with HMRC on behalf of paying clients is legally required to hold a registered Agent Services Account (ASA) and meet a set of minimum standards.
HMRC estimates that approximately 85,000 tax agent businesses are in scope. The requirement applies regardless of where the firm or its clients are located, and regardless of whether the firm considers itself a "tax adviser" in the traditional sense. If you file returns, make payments, send claims, or contact HMRC in any way on behalf of a client for payment, you are in scope.
Registration windows are being phased in based on your firm's existing relationship with HMRC:
Once your registration window opens, you have three months to apply. You may continue to interact with HMRC on behalf of clients during that period and while HMRC considers your application.
To register, your firm must meet three core conditions:
Registration is at firm level, not per individual. However, you will need to identify relevant individuals within your business, typically senior personnel and employees who interact with HMRC. Annual assurance submissions are required on an ongoing basis once registered.
HMRC has been clear: firms that fail to register and continue to interact with HMRC on behalf of clients will be subject to sanctions. In practice, this means HMRC can refuse to deal with your firm, effectively preventing you from acting for your clients. The reputational and commercial consequences of that outcome are significant.
It is also worth noting that if you are a member of a regulated professional body, failure to comply with the TAR scheme may also constitute a breach of your body's own regulatory requirements.
HMRC has introduced a new online service for registration. The process requires you to apply for, or confirm your existing, Agent Services Account. Before you begin, use HMRC's online tool to check whether your firm needs to register and whether you meet the eligibility conditions.
Key steps to take right now:
If your firm is already a member of ICAEW, ACCA, CIOT, ATT, or another recognised professional body, the good news is that you are very likely to meet the minimum standards already. Your AML supervision will typically be in place, and your commitment to PCRT satisfies the Standards for Agents requirement. However, meeting the standards and completing the formal registration are two separate things. You must still register through HMRC's online service before your deadline passes.
Registration is not a one-off exercise. Once registered, your firm must continue to meet the registration conditions and submit annual assurance confirmations to HMRC. If your firm's circumstances change, for example if a relevant individual becomes subject to a disqualifying event, you will need to update your registration accordingly.
HMRC has also signalled that the TAR scheme is part of a broader government initiative to raise standards across the tax advice market. Further requirements and tighter enforcement are expected to follow in the years ahead. Getting your registration right now positions your firm well for whatever comes next.
With the deadline just days away, there is no time to defer this. If your firm holds a Self Assessment or Corporation Tax agent code and has not yet registered, log in to your Agent Services Account today and complete the process. If you are unsure whether your firm is in scope, use HMRC's online checking tool on GOV.UK before the window closes.
TaxCalc will continue to keep you updated as HMRC publishes further guidance on the TAR scheme and its ongoing requirements. If you have questions about how your practice management software can support your compliance obligations, speak to our team.