MMTAR Payroll-Only Firms: Start ASA Packs Before the 18 November Window
HMRC’s second MMTAR window is open for SA/CT agents without an ASA through 18 November — payroll-only firms register from 18 November 2026 to 18 February 2027 and should assemble identity and AML evidence now.
HMRC’s 18 August 2026 press release opens tranche two of Modernising and Mandating Tax Adviser Registration (MMTAR) for advisers with a Self Assessment or Corporation Tax account who still lack an Agent Services Account (ASA). That window runs to 18 November 2026. Advisers who solely provide professional payroll services do not need to register before 18 November — their mandatory window is 18 November 2026 to 18 February 2027.
As of 19 August, payroll-only firms have roughly three months before their own clock starts. HMRC guidance also allows early registration from 18 May 2026. Waiting until November to gather AML supervision evidence, identity packs, and ownership details is how firms collide with year-end payroll peaks and the autumn agent MFA automatic activation wave.
Confirm you are truly payroll-only
GOV.UK’s checker is the source of truth. You only sit in the payroll window if you solely provide third-party payroll services on behalf of clients and do not interact with HMRC in any other way. If the firm also holds SA or CT agent accounts without an ASA, you are in the window that is open today through 18 November — not the later payroll cohort.
In-house employer payroll teams do not register as tax advisers for their own staff. Financial services organisations follow a separate window from 31 December 2026. Do not assume a sister company’s ASA covers every agent ID in the group.
Evidence checklist to start now
Name an owner for each agent ID and run HMRC’s interactive checker before partners invent lists under client pressure.
Assemble identity evidence, AML supervision status, supervisory body details, and ownership information while tranche-two firms are still in the system ahead of you.
Decide whether to apply early or wait for 18 November — early filing reduces the chance that processing overlaps January payroll filing peaks.
Keep MFA workstreams separate: voluntary MFA for the 19 August cohort is already live, and remaining accounts flip automatically between 28 September and 15 October.
How FinnAccountings helps payroll practices
Clean employer ledgers reduce noise while partners build ASA packs. FinnAccountings helps Ireland and UK advisers and business owners prepare bookkeeping and tax packs with Chartered Accountant insight before you or your ICAEW/ACCA or Chartered Accountant (Ireland) adviser files. Start a free trial for review-ready drafts — we prepare records; we do not register you with HMRC or file agent applications on your behalf.
Related reading
Read HMRC’s day-one tranche-two numbers if you also serve SA or CT clients without an ASA.
Use the weekend tranche-two checklist as a template for payroll evidence packs.
Keep agent MFA lockout prevention beside registration work so authenticator failures do not stall ASA applications.
Sources & references
This article draws on official guidance and publications from the sources below.
- 1.Second registration window now open for tax advisers
HM Revenue & Customs · Accessed 2026-08-19
- 2.Check if and when you need to register as a tax adviser with HMRC
HM Revenue & Customs · Accessed 2026-08-19
- 3.MTAR10800 - when tax advisers must register and transitional arrangements
HM Revenue & Customs · Accessed 2026-08-19
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FinnAccountings helps with bookkeeping, tax, and VAT prep for Ireland and the UK — with Chartered Accountant insight on AI drafts. Educational articles are not filing advice.
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