MTD client onboarding needs four things in place before you can sign a client up to Making Tax Digital for Income Tax: an agent services account, the client’s authorisation inside it, software that works with MTD, and the client’s personal and income-source details. You then sign each client up separately through HMRC’s online service. The next cohort, sole traders and landlords with qualifying income over £30,000, must start on 6 April 2027.
MTD client onboarding is the work of identifying which clients are mandated, getting their authorisation into your agent services account, choosing software, setting up digital records and signing them up with HMRC before their start date. For the April 2027 cohort, HMRC tests qualifying income using the 2025 to 2026 Self Assessment return.
Key points
- From 6 April 2027 the threshold falls to qualifying income over £30,000, based on the 2025 to 2026 return; from April 2028 it falls to over £20,000.
- Qualifying income is self-employment and property income before expenses. Employment, partnership profit shares, dividends and pensions do not count.
- Adding your Self Assessment agent code to your agent services account brings existing authorisations across, but it does not sign anyone up.
- A client can have one main agent and any number of supporting agents.
- Exemptions, such as for digitally excluded clients, are applied for through HMRC, which aims to reply within 28 calendar days.
Which clients are mandated in 2027, and how to find them in your SA data
Qualifying income is a client’s total self-employment and property income before expenses (turnover), taken from the Self Assessment return for the earlier tax year. The phased dates on GOV.UK are:
| Start date | Qualifying income | Tested on the return for |
|---|---|---|
| 6 April 2026 | Over £50,000 | 2024 to 2025 |
| 6 April 2027 | Over £30,000 | 2025 to 2026 |
| 6 April 2028 | Over £20,000 | 2026 to 2027 |
The gap most guides skip is timing, and it shapes your whole MTD client onboarding plan. The 2025 to 2026 return is due by 31 January 2027, so for a client whose return is filed in late January, you learn they are in scope about ten weeks before their start date. Do not wait for the return. Run the test on your 2025 to 2026 working papers as soon as the figures are reasonably settled.
A practical way to build the MTD client onboarding list from your practice software:
- Export every Self Assessment client with self-employment or property pages.
- Add gross turnover from each trade and gross rents from each property business. Use the client’s share only for jointly owned property.
- Exclude employment income, partnership profit shares, dividends, State Pension and private pensions.
- Flag anyone over £30,000 as “April 2027”, and anyone between £20,000 and £30,000 as “April 2028, watch”.
- Flag clients near £30,000 for a second check once the return is final.
- Remove anyone already signed up voluntarily or in the April 2026 cohort.
GOV.UK has a narrow exception for joint property: where the client is only told their share of the income after expenses, HMRC uses that figure. HMRC also writes to people above the threshold, confirming they must start by the beginning of the following tax year. Treat that letter as confirmation, and do not rely on it as your trigger.
MTD client onboarding: agent services account and authorisation steps
An agent services account is HMRC’s newer agent account, separate from HMRC online services for agents, and you need it to sign clients up for MTD for Income Tax. If you do not have one, apply for an agent services account first.
- Sign in and choose to add existing Self Assessment authorisations. Enter your Self Assessment agent code. All client authorisations linked to that code move across, and later Self Assessment changes in online services update the account.
- Authorisation requests are often the slowest part of MTD client onboarding. For clients you are not yet authorised for, start a request from the account early and send the client the link to approve.
- Decide your role for each client. A main agent can fully manage the client’s MTD for Income Tax. A supporting agent sees only business and property income details and cannot submit the tax return or view the tax calculation. A bookkeeper doing quarterly updates while you file the return is the typical supporting agent arrangement.
- Tell the client what a main agent cannot do: set up a Direct Debit for them or change how HMRC contacts them.
Software choice and digital records set-up
Digital records are the income and expense records kept in software that works with MTD, from which quarterly updates are sent. GOV.UK says to check with the software provider that its product meets your and the client’s needs. Decide per client:
- Who keeps the records day to day: the client, your team or a bookkeeper.
- Whether the client needs bridging software (spreadsheets plus a submission tool) or full bookkeeping software with bank feeds.
- Standard quarters (ending 5 July, 5 October, 5 January, 5 April) or calendar quarters (ending 30 June, 30 September, 31 December, 31 March). Both share the deadlines 7 August, 7 November, 7 February and 7 May; our calendar of 2026/27 quarterly deadlines shows the periods side by side.
- The opening date for digital records: the first day of the client’s first quarterly period in 2027 to 2028, on whichever basis you choose.
Treat software set-up as part of MTD client onboarding: connect it to HMRC before April, so the first quarter’s records start clean.
What you need to sign each client up
GOV.UK lists the details the sign-up service asks for. Collect them in one request at the start of MTD client onboarding, so you do not go back to the client twice:
| For | Details needed |
|---|---|
| Every client | Full name, date of birth, National Insurance number |
| Sole traders | Business name, business address, nature of the business |
| Each income source | Business or property income start date if it started within the last 2 tax years |
| Sign-up | The tax year the client will start using MTD |
For the 2026 cohort, GOV.UK said HMRC would start signing up, from September 2026, anyone required to use MTD for 2026 to 2027 who had not signed up. Signing clients up yourself as part of MTD client onboarding means their income sources and circumstances are right from the start.
Client communication pack
Most MTD client onboarding delays are clients not replying. Send one pack, in this order:
- A short letter: why they are in scope (their qualifying income figure), their start date and the four quarterly deadlines.
- The authorisation link, if needed, with a note never to share their HMRC sign-in with anyone.
- A details form for the sign-up table above.
- A one-page “how we will keep your records” sheet showing who does what each quarter.
- An engagement letter update or addendum covering quarterly updates and the end-of-year return, with fees. Our client onboarding checklist for UK accounting firms covers the wider engagement steps.
Exemptions and deferrals
Some clients may be exempt. GOV.UK gives being digitally excluded as an example. Clients who are not automatically exempt must apply by contacting HMRC; agents use the Agent Dedicated Line. HMRC aims to respond within 28 calendar days. Exempt clients still file a Self Assessment return. Apply early for anyone likely to qualify, and record the decision on your MTD client onboarding tracker.
An MTD client onboarding tracker template
Keep one row per client and work it weekly from January to April:
| Column | What to record |
|---|---|
| Client and UTR | Name, UTR, partner or manager |
| Qualifying income | 2025 to 2026 figure and source (draft or final return) |
| Cohort | April 2027, April 2028 watch, exempt, already signed up |
| Authorisation | In agent services account: yes or request sent (date) |
| Agent role | Main or supporting, and who else acts |
| Software | Product, record keeper, connected to HMRC (date) |
| Quarter basis | Standard or calendar |
| Client pack | Sent, details returned, engagement letter signed |
| Signed up | Date and confirmation reference |
| First update due | 7 August 2027 |
Penalties in the first year
Under GOV.UK’s MTD penalties guidance, the new late submission points and late payment penalties apply from the tax year a client joins. GOV.UK says there are no penalties for missing a quarterly update deadline in 2026 to 2027; do not assume the April 2027 cohort gets the same easement. Plan MTD client onboarding on the basis that late updates in 2027 to 2028 may attract points. Our MTD for ITSA guide covers the regime in more detail.
FAQs
Do I need an agent services account for MTD for Income Tax?
Yes. GOV.UK says agents sign clients up through the online service using an agent services account, which is separate from HMRC online services for agents. Apply for one before you start MTD client onboarding if you do not have it, then add your Self Assessment agent code so existing client authorisations appear. Adding the code does not sign any client up.
Who has to join MTD for Income Tax in April 2027?
Sole traders and landlords registered for Self Assessment whose qualifying income on their 2025 to 2026 return is over £30,000. Qualifying income is self-employment and property turnover before expenses. Employment income, partnership profit shares, dividends and pensions are left out, and for jointly owned property only the client’s share counts.
What is the difference between a main agent and a supporting agent?
A main agent can fully manage the client’s MTD for Income Tax, including submitting the tax return. A supporting agent can only see business and property income details and cannot submit the return or view the tax calculation. A client can have one main agent at a time and any number of supporting agents.
Can I sign a client up before HMRC writes to them?
Yes, and it is better to. HMRC writes to people above the threshold, but for the April 2027 cohort that depends on the 2025 to 2026 return, which may not be filed until January 2027. Testing qualifying income from your own working papers lets you start MTD client onboarding early: authorise, set up software and sign the client up well before 6 April.
What happens if a client cannot use software?
They may qualify for an exemption, for example if they are digitally excluded. Unless they are automatically exempt, they or you apply by contacting HMRC, with agents using the Agent Dedicated Line. HMRC aims to reply within 28 calendar days. An exempt client still files a Self Assessment return as before.
Get your April 2027 cohort signed up on time
MTD client onboarding for a whole cohort is mostly admin: building the list, chasing authorisations, collecting details and keeping the tracker current. Our client onboarding support and MTD-ready reporting support handle that inside your own systems, while your team makes the scope decisions and signs off. Book a consultation to plan your 2027 cohort.
