Letting an accountant act for you on MTD: what you approve and what stays yours

Marcus is fictional, but plenty of landlords will recognise him. He lets three flats, and for years the same accountant has prepared his Self Assessment return each winter. This autumn the accountant emailed to say they would be looking after Making Tax Digital (MTD) for Income Tax for him as well, and said they would be in touch about what they needed from him. Marcus was happy to hand it over, but he wanted to understand what he was agreeing to, whether the arrangement he already had still counted, and what would still be down to him. This guide walks through those questions as GOV.UK describes them, from the taxpayer’s side.

What changes when you already have an accountant, and what does not

The good news for someone in Marcus’s position is that the relationship itself carries over. Existing client authorisations for Self Assessment are recognised for MTD for Income Tax. What changes is mostly on the accountant’s side, because MTD runs through a different HMRC account for agents, and signing up for MTD is a separate step from authorising someone to act for you.

What does not change is where the responsibility sits. GOV.UK is clear on this point: you are responsible for your own tax affairs, even if you authorise someone to act on your behalf. Handing the work to a professional can take a great deal off your plate, but it does not move the obligation itself, which is why it helps to know which steps are theirs and which are yours.

What your accountant sets up on their side

Before an accountant can act for anyone on MTD, they need the right account with HMRC. Your agent needs an agent services account, which is different from the HMRC online services for agents account they may already use. You do not need to do anything for this part, but it explains why an accountant who has handled your tax return for years may still talk about “setting things up” for MTD.

If they already act for you on Self Assessment, the next step is also theirs. An agent already authorised for your Self Assessment can check whether that authorisation is in their agent services account and, if it is not, add it there using the Self Assessment agent code linked to you. Adding existing Self Assessment authorisations in this way authorises the agent as your main agent for MTD for Income Tax. GOV.UK describes this as something the agent does from their own account, and it does not describe a separate step for you while they do it.

What you may be asked to approve

Whether you are asked to approve anything depends on how you and your accountant are already connected. Your agent needs your permission to sign you up, and an agent who is not authorised by you cannot sign you up for MTD for Income Tax. If they already act for you on Self Assessment, that existing authorisation is the one that carries across, as described above.

A new accountant, or one who has not acted for you on Self Assessment, works the other way round. If your agent is not already authorised for your Self Assessment, they ask you to authorise them through their agent services account. GOV.UK calls the approval itself the digital handshake, and it works like this.

• Your agent sends you an email with a link. You select the link and sign in with the sign in details you use for the tax service you are authorising them for.
• The link expires after 21 days. If you have not responded by then, you need to ask your agent to send another link.
• You may be asked to verify your identity before you can give authorisation to your agent.

When you respond, you are told what you are agreeing to. You see different consent statements depending on whether the agent is asking to be your main agent or a supporting agent, so you know what details they can see and what tasks they can do for you. GOV.UK does not describe the screens in more detail than that, so it is worth reading the statement carefully and asking your accountant if anything in it is unexpected.

One point matters more than any other here, because it protects your own account. You must not give your sign in credentials to your agent or anyone else. An accountant who needs your authorisation will send you a link to approve, rather than asking for your password.

Signing up for MTD when an agent is involved

Authorising your accountant and signing up for MTD are two separate things, and it is easy to assume one includes the other. Adding an authorisation does not automatically sign you up for MTD for Income Tax, so you or your agent still need to go through the sign-up service. If you use an agent, they can sign you up for MTD for Income Tax instead of you doing it yourself. To be signed up, you must be registered for Self Assessment and have submitted a tax return in the last two years.

If your accountant does the sign-up, they will ask you for a few details, which is often the first thing a landlord like Marcus hears about. GOV.UK lists what the agent’s sign-up service needs:

• your full name
• your date of birth
• your National Insurance number
• if you are a sole trader, your business name, which is the name you use on your invoices
• if you are a sole trader, your business address
• if you are a sole trader, the nature of your business (your trade)

For each income source, your agent also needs the date the business started or you started receiving property income, if that was within the last two tax years, and confirms the tax year you will start using MTD for Income Tax. Once that is done, it is worth checking for yourself that the sign-up has gone through. If your agent signs you up for a tax service, sign in to your personal or business tax account to check that the service is displayed, or to add it to your account.

GOV.UK also explains what happens if nobody signs you up in time. GOV.UK says that from September 2026 HMRC will start to sign up anyone who needs to use MTD for Income Tax for the 2026 to 2027 tax year and has not signed up. When HMRC does this, it uses only the information it already holds, which may not include changes to your circumstances since your last tax return. The guide to what to do if HMRC has signed you up explains the steps that follow, including what your agent can do.

Who sends the quarterly updates and the tax return

MTD allows more than one person to help you, which is different from how Self Assessment has worked. You can have only one main agent at a time, but any number of supporting agents, and more than one agent is possible for MTD for Income Tax only. For other tax services, such as Self Assessment, you can only use one agent. For example, a bookkeeper might complete your quarterly updates as a supporting agent, while an accountant finalises your overall tax position and submits your tax return as your main agent.

The two roles have different reach, and the consent statement you see reflects that. A main agent can do almost everything you can. The only things a main agent cannot do are set up a Direct Debit for you and change how you want to be contacted by HMRC. A supporting agent can send quarterly updates but cannot finalise your overall tax position, submit your tax return or view your tax calculation. If you use more than one person, they need to work together, because if more than one agent works on the same business, one combined update must be sent to HMRC for each update period, and one tax return submitted after any adjustments.

What stays your own responsibility

Even with a main agent sending everything for you, GOV.UK keeps a few things with you. The most practical one is checking your return before it goes in. If you authorise your agent for MTD for Income Tax, they can submit tax returns on your behalf, and you must check that the information in your tax return is correct and let your agent know before they submit it. For Marcus, that means reading through the figures his accountant sends at the end of the year and replying to confirm them, rather than assuming silence is enough.

Setting up a Direct Debit and changing how HMRC contacts you are the two things GOV.UK says a main agent cannot do, so those stay with you too. If you change accountant later, there is one more step to remember. If you choose a different main agent, it is your responsibility to tell your current main agent, who will then lose access to your account. You can remove an agent's authorisation in your personal tax account or business tax account. If you remove an agent from MTD for Income Tax, you need to make sure you have also removed them from Self Assessment.

How penalties work, whoever sends your updates, is covered separately in the MTD penalties guide.

If you do not have an accountant yet

If you are looking for someone to take MTD on, the guide to getting help with MTD explains when handing it over tends to make sense, what to ask an accountant, and how to search the professional bodies’ own directories of members. Acrenvo does not recommend any particular firm, and any arrangement you make is between you and them. The main MTD guide covers the wider rules if you want the background first.

Questions people ask about letting an accountant act for them