HMRC Opens Second Tax Adviser Registration Window

This is one of those HMRC announcements that can sound more technical than it really is. The immediate change is that the second registration window for tax advisers is now open, and advisers with Self Assessment or Corporation Tax accounts who do not already have an agent services account have until 18 November 2026 to register. What this means in plain English is simple: if you are paid to deal with HMRC for clients and you sit in that group, you now have a deadline. If you already have an agent services account, known as an ASA, this part of the rollout is not asking you to start again.

The change sits inside HMRC's Modernising and Mandating Tax Adviser Registration programme, usually shortened to MMTAR. According to HMRC, the aim is to move advisers into one digital registration system instead of relying on older, split processes that built up over time. HMRC says the policy is meant to raise standards in the tax advice market, protect taxpayers and back advisers who follow the rules. The government has also set aside £36 million to modernise tax adviser services, which tells us this is not a small administrative tweak but a bigger rebuild of how advisers are recognised online.

There is also an important point about who counts as a tax adviser. HMRC says anyone who is paid to interact with the department on somebody else's behalf about their tax affairs is generally treated as a tax adviser unless an exemption applies. Not everybody needs to act now. Advisers who only provide professional payroll services do not need to register before 18 November 2026, because their window runs from 18 November 2026 to 18 February 2027. Financial services organisations have a later start again and do not need to register before 31 December 2026. Advisers who already hold an ASA do not need to register again and will be moved to the new service by 31 March 2027. HMRC says it will contact them through their account if it needs extra information.

For firms trying to work out the next step, HMRC says registration is free and done online through GOV.UK. There is a checker tool to help advisers see whether they need to apply now, and applicants must meet HMRC's registration conditions before they can get an ASA. The first registration window gives a sense of scale. HMRC says more than 4,000 applications were submitted and more than 2,000 accounts were created in phase one, which ran from 18 May 2026 to 18 August 2026 and mainly targeted the smallest agent group. If you missed that earlier window, or if you are new to the market, HMRC says you should register as soon as possible.

One detail that will matter to small firms is that applying does not mean you have to stop working while HMRC processes the paperwork. HMRC says advisers who have submitted an application and received a registration number can keep dealing with the department for clients, and access to online services will not be cut off in the short term. That breathing space matters, because the penalty for doing nothing could be much more serious. HMRC says it may limit an adviser's ability to act for clients if they fail to register when required, and advisers who keep operating without meeting the new rules could face enforcement action, including financial penalties.

If you are a business owner who uses a tax adviser, this is worth asking about now rather than near the deadline. A quick check with your adviser on whether they already have an ASA, or whether they need to register in this second window, could save confusion later if HMRC tightens access. What it means for learners and newer business owners is this: regulation often shows up first as admin. Behind the acronyms, the real question is who HMRC recognises as a trusted representative for your tax affairs. When that recognition changes, the practical effect can land on clients as well as advisers.

Robert Jones, HMRC's Director of Intermediaries, has framed the rollout as a way to strengthen trust and transparency in the tax advice market. That is the official argument, and it will sound reasonable to many advisers. Even so, every new compliance deadline brings extra work, especially for smaller practices that do not have big admin teams. So the safest reading of this update is a practical one. If you advise on Self Assessment or Corporation Tax and do not have an ASA, check the GOV.UK tool now and aim to register well before 18 November 2026. If you are not in that group, check your place in the phased timetable and keep a note of the next date that applies to you.