Check with your existing software provider about what MTD-ready products they have available, or in development.

You may need (or choose) to use different software for clients in MTD. HMRC’s guidance on choosing MTD software, and MTD software finder tool can help identify suitable products.

You may have clients who will deal with their own their own digital record keeping under MTD. Some may also want to file quarterly updates themselves, with you as agent stepping in to look after the year-end process and submit the MTD tax return.

Clients do not need to use the same software that you use as their agent. Data can be electronically transferred between client and agent. If the client is filing their own quarterly updates, the data they submit will be drawn down from HMRC and pre-populated in your agent software ready for the year-end process once you are authorised as agent and have correctly linked your software with your Agent Services Account.

A spreadsheet may be sufficient to enable your clients to maintain their own digital records. For clients who choose to file quarterly updates themselves, ‘bridging products’ are available to take the data from a spreadsheet and file it with HMRC each quarter. HMRC’s guidance on choosing MTD software, and MTD software finder tool can help identify suitable products.

Only one ASA can be allocated per legal entity. You might have previously set up an ASA to access: MTD for VAT services, the Trust Registration Service, or the ’60-day’ Capital Gains Tax reporting service.

Firms which are already registered with HMRC as an Agent but don’t have an ASA can set up an Agent Services Account immediately. This can only be done by the owner/manager in the case of sole traders, by directors of incorporated firms and by partners of partnerships and LLPs.

If you’re a new tax agent and haven’t registered with HMRC yet, you’ll need to register as an Agent with HMRC. Once HMRC confirm you’re registered as an agent, you’ll be able to set up an ASA online (as above). 

Having set up your ASA, depending on the size of your firm, you may wish to consider what user profiles are necessary.

The person who sets up the ASA will become an Administrator, and will have powers to add Standard users as well as other Administrators. Further guidance on ASA user profiles and permissions is available online. 

HMRC have published guidance on how to add authorisations to your Agent Services Account, which includes linking it with your Online Services account. 

Linking the accounts allows your existing clients’ Self-Assessment authorisations to map across to your ASA. A ‘live’ link is created, meaning if a client authorises you as agent in one service, that authorisation should automatically transfer across to the other.

Existing client authorisations from the Online Services account will map across to the ASA as ‘main agent’ authorisations – see Multiple agents below.

Linking the accounts does not prevent you from accessing a client’s details in the Online Services account. It also doesn’t result in affected clients being registered for MTD. This step can therefore be carried out at any time in the run up to MTD coming into effect for your clients.

For new clients in MTD, agents will need to arrange client authorisation via their ASA (using the ‘digital handshake’ procedure), making sure to request authorisation as either main agent or a supporting agent, having agreed the appropriate roles with the client (see Multiple agents below). 

A common scenario might be that a tax agent prepares their client’s Self-Assessment returns. That client has to join MTD and wants their agent to continue filing their MTD tax returns. That agent will therefore need to become their main agent.

However, the main agent might not be best placed to handle day-to-day digital record keeping and/or submitting quarterly updates. So, the taxpayer might choose to appoint a bookkeeper as a supporting agent to look after those tasks, with the main agent remaining responsible for the MTD tax return.

Alternatively, the taxpayer might choose to keep digital records and submit quarterly updates to HMRC themselves, but ask a main agent to deal with their MTD tax return. In this scenario, there would be no need for a supporting agent to be appointed.

A taxpayer can have one main agent and/or any number of supporting agents.

Main agents and supporting agents have different levels of permissions regarding a client’s tax affairs – see HMRC’s comparison chart of authorised actions for main and supporting agents for details.

When you link your Online Services account with your ASA, existing client authorisations will copy across to your ASA with ‘main agent’ permissions. This should provide continuity where an agent is already authorised to act for Self-Assessment clients. 

For new clients in MTD, agents will need to arrange client authorisation via their ASA (using the ‘digital handshake’ procedure), making sure to request authorisation as either main agent or a supporting agent, having agreed the appropriate roles with the client.

Agents will be accustomed to seeing a client list in their Online Services account. The ASA does not currently offer this facility. Instead, you will need to search for clients within your ASA individually using the client’s National Insurance number.

Alternatively, we understand some software developers have built the facility to view a client list and payments/credit balances/filing status etc within their MTD software.

This type of information is available via the ASA, just as it would be via the Online Services account for clients in ‘classic’ Self-Assessment.

The amount of information and services available within the ASA depends on whether you are authorised as a main agent or as a supporting agent - see Multiple agents above. 

We understand some software packages may display this type of information fed from the client’s HMRC record without the agent needing to log in separately to any HMRC services.

Agents can register most clients in advance for MTD. However, there are currently restrictions which mean taxpayers with certain circumstances are unable to register for MTD - this primarily affects those with circumstances not supported by the testing phase. We understand this currently includes taxpayers:

• preparing accounts to any date other than 31 March or 6 April.
• with partnership income
• with trust income
• who may want to claim profits averaging (farmers or creative artists)

HMRC have published details of further restrictions on signing up for MTD in advance. We are awaiting confirmation from HMRC as to when these restrictions will be lifted.

Feedback indicates registration generally takes less than five minutes per client, but this could still add up to a considerable amount of time, especially for larger firms. Agents will need to plan ahead to ensure all affected clients are registered by the relevant deadline.

There is no bulk registration service for clients in scope of MTD, so clients will need to be registered individually once they have agreed for you to register them. You will also need to be authorised by the client as either a main agent or supporting agent before you can register them for MTD. 

The MTD sign up facility for agents is available online. At the time of writing this covers both registration for the testing phase and for the mandation year, so ensure you choose the correct option.

HMRC will not register clients/taxpayers for MTD automatically, and neither will registrations from MTD for VAT carry over automatically to MTD for Income Tax. See the Exemptions section of our MTD FAQs for more information. 

Joining testing could help you to understand in advance what MTD will involve. It gives you a chance to test your systems and processes, and may help you better understand the time commitments and possible fees for when MTD becomes compulsory. 

HMRC have a dedicated support team to help taxpayers in the testing program, and there are no penalties during testing for late submissions of quarterly updates – see the Penalties section of our MTD FAQs for more details. 

The ‘public’ testing phase began in April 2025. However, you can join at any time up until April 2026, provided you have digital records in place from the start of the tax year.

You’ll need to discuss testing with any clients you think might be suitable, and confirm that they’re eligible to join the MTD testing phase. 

Once you’ve confirmed your client is eligible to join testing, you’ll need their permission to enrol them. You’ll also need to have suitable software in place, and have confirmed that your software provider can support you through the testing phase.

Subject to that, details of how to sign up for MTD testing can be found on GOV.UK.