☐ Qualifying income = self-employment plus UK property income before expenses (turnover); joint property counts at their share. Over £50,000 in 2024-25 → from 6 April 2026; over £30,000 in 2025-26 → from 6 April 2027; over £20,000 in 2026-27 → from 6 April 2028. Checker.
☐ Check whether an exemption applies (for example, digital exclusion).
☐ Partnerships join later; HMRC hasn't set the date.
2. Authorisation
☐ You need an agent services account. It is different from your HMRC online services for agents account.
☐ Existing Self Assessment authorisations are recognised for MTD for Income Tax: check each one is in your agent services account, and add it if not.
☐ Not authorised for Self Assessment? Ask the client to authorise you from your agent services account.
☐ Get the client's permission to sign them up.
3. Sign-up
☐ The client must be registered for Self Assessment and have sent a tax return in the last 2 years.
☐ Sign each client up individually: adding authorisations doesn't sign them up.
☐ From September 2026 HMRC signs up people who need MTD and haven't signed up, using only the information it holds. If HMRC signed your client up, check their income sources and circumstances are up to date.
☐ The return for the year before they start still has to be filed as usual.
4. Software
☐ Choose software that works with MTD for Income Tax; check with the provider that it covers this client (sole trade, property, or both).
☐ Spreadsheets can be used with bridging software, as long as the records are digitally linked.
☐ Bank feeds help, but you may need to add the Self Assessment category, and some transactions need adding by hand.
5. What to collect from the client
☐ Name, National Insurance number, Self Assessment UTR, address, email and mobile, and how they prefer to be asked (email or WhatsApp).
☐ Every source of self-employment and property income: each business and each property (with any joint owners and their share).
☐ Business bank and card accounts, any letting agent, and any software or spreadsheet they already use.
☐ Whether their accounting period runs to 5 April or 31 March (standard or calendar update periods).
6. Digital records
☐ For each income and expense: the amount, the date and the category.
☐ Records for a quarter must exist before that quarter's update is sent.
☐ Signed up partway through the year? Catch up records from the start of the tax year.
7. Deadlines
☐ Quarterly updates are due 7 August, 7 November, 7 February and 7 May; the tax return by 31 January after the tax year. Calculator with a calendar file.
☐ 2026-27: no penalty points for late quarterly updates; points still apply to late tax returns. From 2027-28, a point per late update and £200 at 4 points.
8. Your practice
☐ Update the engagement letter and fee for four quarterly updates a year.
☐ Set an ask-by date for each quarter (about 10 days before the deadline) and tell the client now.