Agents & Accountants

Practical guidance for ASA setup, client authorisations, sign-up and multi-agent working under MTD for Income Tax.

If you manage MTD clients, this guide covers what usually causes the most friction: getting the Agent Services Account right, placing the correct client authorisations, signing clients up, and deciding who does what when more than one agent is involved. HMRC's model is built around compatible software, quarterly updates, and a year-end tax return submitted through software, with mandation arriving in phases from April 2026.

If your firm keeps working papers in spreadsheets, that remains a valid route. HMRC allows spreadsheets when connected by bridging software. Where more than one product is used, the linkage must be digital rather than manual — which is why a spreadsheet-friendly workflow can stay practical without overselling complexity.

Start here if you are onboarding MTD clients

Check who is in scope first. A client needs MTD for Income Tax if they are in Self Assessment, have self-employment or property income, and qualifying income is above the threshold for the relevant year:

6 April 2026 — qualifying income above £50,000 (2024/25 return)
6 April 2027 — above £30,000 (2025/26 return)
6 April 2028 — above £20,000 (2026/27 return)

Then work in order: create or check the ASA, add or request client authorisations, choose compatible software, and sign each client up separately. HMRC does not offer bulk MTD sign-up for Income Tax.