HMRC research involving 873 agents shows why this distinction matters. Seventy-five per cent of agents said they used both ASA and Online Services for Agents. This shows that many firms need to work across both systems rather than relying on one account alone.

With this distinction clear, the next question is who actually needs an ASA.

Who Needs an HMRC Agent Services Account?

If you provide tax advice to clients and interact with HMRC on their behalf, you may be legally required to register with HMRC as a tax adviser and obtain an Agent Services Account. The exact requirements depend on your business and the services you provide. 

For example, an ASA is required when acting as an agent for Making Tax Digital for Income Tax. HMRC also uses ASA for other supported digital services, so firms should always check the requirements for the specific services they provide. Depending on the services they provide, firms may also need to use OSA for services such as Corporation Tax.

But setting up the account is only one part of the process.

Once the account is active, your firm may also need to:

• Obtain the correct authorisation from each client.
• Add and manage client authorisations.
• Set up individual staff access.
• Give staff the right roles and permissions.
• Make sure the required software is compatible with the relevant HMRC service.
• Maintain access to OSA where certain services still require it.

These parts work together. An account can be correctly registered and still not give a firm everything it needs to manage client tax affairs effectively.

What Can Accountants Use an Agent Services Account For?

The value of an ASA depends on how well it works with the other parts of your firm’s HMRC setup, particularly client authorisations, staff access and other HMRC systems.

Managing Client Authorisations

Client authorisation is at the heart of acting for clients through HMRC’s online services.

Creating an ASA does not automatically give your firm permission to act for every client. For supported services, agents need to request authorisation through the relevant HMRC process.

The exact method can depend on the tax service. For example, the digital handshake allows an agent to send an authorisation request to a client, who can then approve it through the relevant HMRC service.

Keeping track of these authorisations matters. Your firm needs to know which clients have authorised you and which tax services those authorisations cover.

Supporting Making Tax Digital

Client authorisation is only one part of the digital tax process.

Making Tax Digital has made it even more important for firms to have the right account access, authorisations and software connections in place.

For Making Tax Digital for Income Tax, agents need an ASA and the appropriate client authorisation before signing clients up. Clients also need compatible software and must be correctly set up for the service.

This is why MTD preparation should not be treated as a software issue alone. The account, authorisation and software all need to work together.

How to Set Up an HMRC Agent Services Account Correctly

Once you know which services require an ASA, the next step is to set up the account and manage the access around it.

A reliable setup starts with accurate registration information and continues with proper client authorisations and controlled staff access.

1. Prepare Your Registration Details

Before applying, make sure the business and agent information provided to HMRC is accurate and up to date.

HMRC may ask for additional information or carry out checks during registration. Having accurate business and contact details can help reduce unnecessary delays.

Where relevant, firms should also make sure their anti-money laundering supervision information is correct and current.

2. Complete HMRC’s Verification Checks

HMRC may carry out checks before giving access to the account.

Responding promptly to requests and providing accurate information can help keep the process moving. Once the account is active, keep your firm’s registration and contact information up to date rather than waiting until an access problem appears.

3. Set Up Client Authorisations

After registering as a tax agent, you need authorisation from clients before you can deal with HMRC on their behalf.

The authorisation process depends on the tax service. Digital authorisation may be available for some services, while other services may use different routes.

One important rule should always be followed: do not ask clients to share their HMRC login details. Use the relevant HMRC authorisation process instead.

4. Manage Staff Access

An accounting firm’s ASA should not rely on shared login details.

HMRC allows administrators to create additional users and assign roles. When someone joins the firm, changes responsibilities or leaves, their access should be reviewed promptly.

This helps make sure current employees have the access they need while reducing the risk of former employees keeping access after they leave.

How to Maintain Your HMRC Agent Setup

Getting your accounts set up correctly is important. Keeping them up to date is what helps prevent many avoidable access problems.

A practical review should cover:

• ASA and OSA access
• Client authorisations
• Staff roles and permissions
• Agent registration and contact details
• Anti-money laundering supervision details where applicable
• MTD client status
• Software connections and compatibility
• Current HMRC service issues or planned downtime

These checks become especially important when your firm takes on new clients, changes staff, introduces new software or starts using additional HMRC digital services.

Regular reviews can help you find problems before they affect client work.

Common HMRC Agent Services Account Problems and How to Fix Them

Even a well-managed setup can experience access problems.

When something goes wrong, looking only at the ASA may not reveal the real cause. The problem could be connected to a client authorisation, staff permissions, OSA access or software.