This post sets out who this affects, what automatic enrolment actually means in practice, and what your firm should be doing now to avoid being caught out by clients who get pulled into MTD without your knowledge.
Around 864,000 taxpayers were mandated into MTD for IT for the 2026/27 tax year, based on qualifying income over £50,000 on their 2024/25 Self Assessment returns. Of those, HMRC's own figures show that just over 570,000 have registered, and more than 436,000 successfully filed their first quarterly update by the 7 August deadline.
That leaves a gap of roughly 294,000 taxpayers who were mandated but have not signed up. It is this group that HMRC will begin automatically enrolling from next month, with the process running in stages through September and beyond. Detailed guidance on exactly how the rollout will work is expected this month, but HMRC has confirmed that affected taxpayers will receive a letter or digital message explaining what happens next.
Importantly, this automatic enrolment only applies to the 2026/27 cohort. Clients who will be newly mandated in April 2027 (qualifying income over £30,000) and April 2028 (over £20,000) will still need to go through the standard, self-directed sign-up process when their turn comes.
Once HMRC enrols a taxpayer, they will need to log into their personal or business tax account to check that HMRC's records are accurate; in particular, confirming which businesses are still active and flagging any that have closed, so they aren't left with an ongoing filing obligation for a business that no longer trades.
For firms, this creates a practical problem. Agent Services Accounts currently show enrolled clients only by HMRC reference number, with no name or other identifying detail attached. That makes it genuinely difficult for a firm to work out which of its clients have just been swept into MTD, especially across a large client list. On top of that, exemption applications submitted months ago in some cases still haven't been processed, and clients without a Personal Tax Account, or who struggle with HMRC's identity verification, may find themselves enrolled with no straightforward way to engage with the requirement at all.
It would be easy to read this as good news: HMRC doing the chasing, rather than firms having to do it. In practice, the advantage is limited. A client enrolled automatically, without your input, may end up mandated on a business that's ceased, or without the exemption they were entitled to, purely because HMRC didn't have up to date information. Untangling that after the fact is more work than getting ahead of it now, and it's your firm clients will call when a letter from HMRC arrives that they don't understand.
As one practitioner put it in discussion of the change, there were real benefits to agent-led sign-up that this shift away from puts at risk. The practical takeaway for firms is the same either way: the less HMRC has to guess about a client's circumstances, the less clean-up work you'll have in October and November.
TaxCalc is HMRC-recognised and MTD-ready, giving practices a single, reliable place to manage MTD obligations alongside the rest of their compliance workload. The MTD Quarterly Filer within TaxCalc lets you prepare and submit quarterly updates directly to HMRC, with the same validation checks and familiar interface your team already relies on for tax return and accounts production, making it easier to spot problems, such as a client who shouldn't be in scope, before they become filing errors.
Because TaxCalc integrates directly with Xero, QuickBooks, and FreeAgent, your team can pull bookkeeping data straight into the quarterly update workflow without rekeying, which matters even more as your in-scope client list grows through HMRC's own enrolment activity rather than entirely through your firm's planning.
If your practice wants a refresher on managing MTD obligations across a growing client base, TaxCalc's webinars and supporting resources are available to help your team build confidence quickly.
Automatic enrolment of 2026/27 stragglers is very likely a preview of how HMRC will handle future cohorts too. With the qualifying income threshold dropping to £30,000 in April 2027 and £20,000 in April 2028, the pool of clients who could be pulled into MTD without warning will only grow. Firms that build a habitual process now, regularly reconciling their Agent Services Account against their client list, chasing exemptions promptly, and briefing clients early, will be far better placed to handle each new wave without a scramble.
It's also worth remembering that this sits inside a wider run of change for accounting practices this year, from Companies House identity verification deadlines to speculation ahead of the 28 October Budget. Firms that treat MTD monitoring as a standing item on the practice's compliance calendar, rather than a one-off task, will free up capacity to deal with everything else 2026 has in store.
TaxCalc is trusted by more than 12,000 UK accounting practices to handle tax, accounts, and practice management in one place. If you would like to see how TaxCalc's MTD tools can help your firm stay ahead of HMRC's enrolment activity and manage quarterly filing efficiently and accurately, take a free trial or request a quote today.