MTD for Income Tax for accountants: getting your clients ready

To act for clients under Making Tax Digital (MTD) for Income Tax, you need an agent services account, an MTD for Income Tax authorisation for each client (as their main or supporting agent), and each client signed up before you can send their quarterly updates and tax return through compatible software. Clients with qualifying income over £50,000 on their 2024-25 return should already be in from 6 April 2026, with the £30,000 group joining on 6 April 2027 and the £20,000 group on 6 April 2028.

This guide for small practices walks through each step and ends with a dated checklist to 31 January 2028. Each rule links to HMRC's guidance, mostly its MTD for Income Tax as an agent: step by step collection.

Key facts for practices

Step 1: get an MTD agent services account

HMRC's guidance on applying for an agent services account says the ASA is how tax advisers access HMRC's online services, and HMRC's sign-up guidance for agents says it's different from your HMRC online services for agents account.

To apply, you'll need:

• your business Government Gateway user ID and password (and your personal one if you're a sole trader)
• your firm's UTR and the postcode linked to it
• your company registration number and VAT number, if you have them
• the name of your anti-money laundering supervisory body and proof you're supervised
• names and contact details of relevant people in the business

HMRC will reject the application if your anti-money laundering supervision has been applied for but not yet approved. Once the account is set up, HMRC suggests creating a Government Gateway user ID for each member of staff and setting permissions for their access to services and clients.

The same page notes that HMRC is bringing in registration for paid tax advisers in stages, so check where your practice stands.

Step 2: MTD agent authorisation for each client

You can't sign a client up for MTD for Income Tax unless they've authorised you. How you get that depends on whether you already act for them for Self Assessment.

Clients you already act for on Self Assessment

HMRC says existing Self Assessment authorisations are recognised for MTD for Income Tax. You need to make sure they've been added to your ASA:

1. Sign in to your ASA and select "Add existing Self Assessment authorisations to your agent services account".
2. Check which Self Assessment agent codes are already listed. You'll see codes, not individual clients.
3. Add any missing codes. Each code brings across all the client authorisations linked to it, and you can repeat this for more than one code.

According to HMRC's guide to adding client authorisations, adding a code:

• authorises you as main agent for those clients
• doesn't remove access in your HMRC online services account, which you keep using for Self Assessment and for clients not in MTD for Income Tax
• doesn't sign anyone up; each client still has to go through sign-up
• links your two accounts, so client changes you make for Self Assessment update your ASA permissions

New clients, or clients you don't act for on Self Assessment

Sign in to your ASA and follow the steps to ask the client to authorise you. HMRC calls this the digital handshake. Its guidance on authorising an agent says the client gets an email with a link, signs in with their own details and may need to verify their identity. The link expires after 21 days, after which you'll need to send a new one. Clients must never give you their sign-in details, and you must not use them.

Main agent or supporting agent

HMRC's guidance on choosing agents for MTD for Income Tax lets a client have one main agent and any number of supporting agents. When you request authorisation, the client sees a different consent statement for each role.

HMRC's own example: a bookkeeper who does the quarterly updates is a supporting agent, and an accountant who finalises the tax position and submits the return is the main agent. If more than one agent works on the same business, you must make sure one combined update goes to HMRC for each period and one tax return after adjustments.

If a client appoints a new main agent, the previous one loses access, and it's the client's job to tell you.

Step 3: sign your clients up

HMRC's agent sign-up guidance says that if a client needs MTD for Income Tax for 2026-27, you should sign them up now. Before you do, check whether they're exempt. To be signed up, a client must be registered for Self Assessment and have submitted a tax return in the last 2 years.

You'll need the client's:

• full name, date of birth and National Insurance number
• for sole traders, the business name used on invoices, the business address and the nature of the trade
• the start date of any business or property income that began in the last 2 tax years
• confirmation of the tax year they'll start using MTD for Income Tax

If a client has more than one self-employment or property business, check each one in the service and add any that are missing, including income that has stopped since their last return. If all of a client's self-employment and property income has stopped, HMRC says to tell it before the start of the next tax year. The sign-up service doesn't ask about other income such as interest or dividends; that goes into the software before the tax return is submitted. You sign in with the same user ID and password as your ASA.

Clients HMRC has signed up

From September 2026, HMRC started signing up people who need MTD for Income Tax for 2026-27 and hadn't signed up. HMRC uses only the information it already holds, which may miss recent changes. If a client tells you HMRC has signed them up, follow HMRC's guidance on what to do if HMRC has signed you up.

Clients who want to volunteer

Clients can sign up for the current tax year or the next one before they have to. Any missed quarterly updates for the year so far then need sending. Volunteers are on different penalty rules, and once they agree to the new penalties they can't go back, so talk that through with the client first.

Which clients come in, and when

HMRC's guidance on when clients need MTD for Income Tax bases each start date on qualifying income from one tax return:

Qualifying income is self-employment turnover plus gross property income, before expenses. Employment income, partnership profit shares, dividends and pensions don't count, and joint property counts at the client's share. Our qualifying income guide goes through the rules, and Do I need MTD for Income Tax? covers exemptions.

In practice, the 2025-26 returns you file by 31 January 2027 decide who joins in April 2027.

What MTD ITSA means for your workload

For each client in MTD for Income Tax, HMRC's quarterly updates guidance requires a quarterly update for each business. All UK property is one business, foreign property is another, and each trade is a separate business. A client who trades and lets UK property needs two updates every quarter, plus one tax return at year end.

Updates are cumulative category totals, due on 7 August, 7 November, 7 February and 7 May. Our guides for sole traders and landlords cover the client-side record rules, including joint property and letting agent statements.

Year end and the tax return

After the fourth update, you make adjustments, add other income and submit the tax return through software by 31 January. HMRC says you can only submit a client's return if you're their main agent. Before submitting, you must:

1. view and check the tax calculation
2. share a copy of the information being submitted with the client
3. ask the client to check it and give written confirmation that it's correct and complete
4. declare that the information and calculation are correct and complete to the best of your knowledge

If the client or a supporting agent sent the quarterly updates, you can see them in your software but not their digital records.

Penalties: the 2026-27 soft landing

HMRC's sign-up guidance for agents and its penalties guidance say there are no penalty points for late quarterly updates in 2026-27. Late tax returns and late payment are still penalised, and every update must be sent before the tax return can be submitted.

From 2027-28, each missed quarterly update or return deadline earns a point (one per deadline, however many businesses the client has), and 4 points means a £200 penalty. Our penalties guide covers the detail, including late payment.

A checklist for the coming months

Now (October 2026)

• Set up your ASA if you haven't, with staff user IDs and permissions.
• Add all your Self Assessment agent codes to the ASA.
• List clients with qualifying income over £50,000 on their 2024-25 returns, and check each is signed up, exempt, or has stopped trading.
• Ask clients whether HMRC has written to say it's signed them up, and check the income sources it holds.
• Choose software, and check it supports each client's income sources and update periods.

By Friday 6 November 2026

• Send the second quarterly update (6 April to 5 October 2026, or 1 April to 30 September 2026 on calendar periods) for every business. 7 November is a Saturday. Our 7 November guide has more.
• Send any overdue first quarter updates. They're cumulative, so one update can bring a late starter up to date.

By 31 January 2027

• File 2025-26 returns in the usual way, under the old penalty rules.
• Flag clients whose 2025-26 qualifying income is over £30,000. They join on 6 April 2027.

7 February 2027 and before 6 April 2027

• Third quarterly update due 7 February 2027.
• Get authorisations in place and sign up the April 2027 group. Late quarterly updates earn penalty points from 2027-28.

7 May 2027 and after

• Fourth 2026-27 update due 7 May 2027. Then year-end adjustments.

By 31 January 2028

• Submit 2026-27 tax returns through software as main agent, with each client's written confirmation, and make sure the tax is paid.

All the dates are in MTD for Income Tax deadlines 2026-27. For questions GOV.UK doesn't answer, HMRC's Agent Dedicated Line has a webchat that covers MTD for Income Tax.

How AATAX works for practices

AATAX is HMRC-recognised MTD for Income Tax software. Its HMRC listing (reference D6Q7XM) shows agent software as ready now.

You connect AATAX to HMRC with your agent sign-in, then add each MTD for Income Tax client by their National Insurance number once they've authorised you. Clients reply to reminders with bank statements, receipts or spreadsheets, or use a secure upload link, which they open with a code sent by email. AATAX reads your clients' receipts and statements, and your team reviews and confirms.

A work queue shows what's due and overdue across the practice, with each client's deadlines tracked, so you can file every quarterly update from one place.

Pricing is a yearly package by how many clients you have, ex VAT: £99 for up to 20 clients, £189 for up to 50, and £299 for up to 200, plus £0.35 for each client over 200. Every package has unlimited users and 500 AI credits per client a year (about 250 pages read), and VAT returns are an add-on for 25% more. Your first 3 clients are free for 12 months, and you pay only when you have more.

See our MTD software for accountants for an overview.

Book a demo

See how AATAX handles MTD for Income Tax using your own client book. Book a 30-minute demo, or create a practice account and start with 3 clients free.

Sources (GOV.UK, checked 10 October 2026)

• Making Tax Digital for Income Tax as an agent: step by step
• Apply for an agent services account
• Add your client authorisations for Making Tax Digital for Income Tax
• Choose agents for Making Tax Digital for Income Tax
• Authorise an agent to deal with certain tax services for you
• Sign up your client for Making Tax Digital for Income Tax
• Find out if and when you need to use Making Tax Digital for Income Tax
• Find out if you can get an exemption from Making Tax Digital for Income Tax
• Check what to do if HMRC has signed you up for Making Tax Digital for Income Tax
• Use Making Tax Digital for Income Tax: Send quarterly updates
• Use Making Tax Digital for Income Tax: Submit your tax return
• Penalties for Making Tax Digital for Income Tax
• Penalties for Income Tax Self Assessment volunteers
• Agent Dedicated Line: Self Assessment or PAYE for individuals
• Find software that works with Making Tax Digital for Income Tax (HMRC software finder, including AATAX's listing)

This page is general guidance for agents, not tax advice. Check HMRC's agent guidance for your clients' circumstances.