Key takeaways

  • An agent services account (ASA) is HMRC's account for tax agents, and applying for one is how advisers now register with HMRC as tax advisers.
  • Advisers with Self Assessment or Corporation Tax agent accounts but no ASA must register by 18 November 2026.
  • Since 1 October 2026 HMRC rejects ASA applications where anti-money laundering supervision has been applied for but not yet approved.
  • You link a new client by sending an authorisation request link from the ASA, which expires after 21 days.
  • HMRC says advisers do not need to consolidate legacy agent codes or move every client authorisation onto the ASA to register.
  • MTD for Income Tax, MTD for VAT, trusts, estates and CGT on UK property accounts are handled through the ASA; Self Assessment and Corporation Tax still use HMRC online services for agents.

An HMRC agent services account (ASA) is the online account tax agents use for HMRC’s newer services, and since 18 May 2026 applying for one is how you register as a tax adviser. Advisers who have Self Assessment or Corporation Tax agent accounts but no ASA must register by 18 November 2026. Once set up, you link clients by sending them an authorisation link that lasts 21 days.

What is an agent services account?

The ASA is HMRC’s agent account for its digital services, separate from the older HMRC online services for agents account. Each ASA has an Agent Reference Number (ARN). HMRC’s online services for agents collection splits the services like this:

ServiceAccount used
MTD for Income Tax sign-upAgent services account
VAT client detailsAgent services account
Trusts and estates registrationAgent services account
CGT on UK propertyAgent services account
Pillar 2 top-up taxesAgent services account
Self Assessment, Corporation Tax, PAYEHMRC online services for agents

Most firms therefore run both accounts side by side.

Do you need one now?

You need one if you are paid to deal with HMRC about someone else’s tax and fall into a registration window. HMRC set these dates in its 18 August 2026 announcement:

  • No agent account of any kind: the window closed on 18 August 2026, so register now.
  • Self Assessment or Corporation Tax agent account, no ASA: register by 18 November 2026.
  • Payroll-only providers: 18 November 2026 to 18 February 2027.
  • Already hold an ASA: do not register again; HMRC says you will move to the new service by 31 March 2027.

If you are unsure, see the 18 November deadline explained and our guide for trustees and executors.

What you need before you apply

HMRC’s apply for an agent services account page, updated on 13 October 2026, lists these:

  • a business Government Gateway user ID and password (you can create one at sign-in)
  • a personal Government Gateway user ID if you are a sole trader
  • your firm’s Unique Taxpayer Reference (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 (AML) supervisor and proof you are supervised
  • names and contact details of the relevant individuals in your business

AML supervision must be approved first. Since 1 October 2026 HMRC rejects applications where supervision has only been applied for. See AML registration for accountants.

How to set up your agent services account

The application takes three steps.

  1. Sign in with your business Government Gateway user ID.
  2. Apply through HMRC’s online agent registration service.
  3. Share the link the service gives you with each relevant individual. They sign in with their own Government Gateway ID, not the business one, and add their details.

HMRC then checks the business and each relevant individual against its registration conditions, such as tax compliance and no relevant convictions. It gives no standard processing time. You can track progress with HMRC’s application status service and keep dealing with HMRC while your application is considered.

You link a new client with a digital authorisation request. HMRC calls this the digital handshake.

  1. Sign in to your agent services account.
  2. Select “Ask a client to authorise you”.
  3. Enter the client’s details. The details needed vary by tax.
  4. Copy the authorisation request link from the final page and send it to the client.
  5. The client signs in with the details they use for that tax and accepts.

The link expires after 21 days. If the client does not use it in time, you start again. The “Manage your authorisation requests from the last 30 days” page shows each request’s status.

Existing clients can be copied across from your HMRC online services for agents account. Where no online route exists, HMRC’s guidance on authorising an agent says clients can use the paper form 64-8.

Do you have to move every client onto the ASA?

No. An HMRC policy representative told the Chartered Institute of Payroll Professionals on 27 October 2026 that registration does not require firms to consolidate legacy agent codes. HMRC is building a way to link legacy codes to your ARN so client relationships carry over, and says it will publish guidance on actions and deadlines.

Giving staff access

Administrators add staff from the “Manage account” page. HMRC offers two roles:

  • Administrator: can access all services, enrol in services and add or remove users.
  • Standard user: can only use the services an administrator assigns.

Each person needs their own sign-in. HMRC also says you must not use the account to suggest HMRC endorses your firm.

What to do now

  1. Check which agent accounts you hold. If you have Self Assessment or Corporation Tax codes but no ASA, apply before 18 November 2026.
  2. Confirm your AML supervision is approved and keep the certificate.
  3. List your relevant individuals and send them the link on the day you apply.
  4. Set up staff users and roles.
  5. Prepare client links for MTD for Income Tax ahead of April 2027. See how to sign up for MTD for Income Tax.

For phone help, see HMRC telephone numbers.

Frequently asked questions

What is an HMRC agent services account?

It is HMRC’s online account for tax agents using its newer digital services, such as MTD. Applying for one is now how you register as a tax adviser.

21 days. If the client does not respond in that time, you must send a new request.

Can I apply for an ASA before my AML supervision is approved?

No. Since 1 October 2026 HMRC rejects applications where AML supervision has been applied for but not approved.

Do I need to register again if I already have an ASA?

No. HMRC says existing ASA holders do not register again and will move to the new service by 31 March 2027.

Is there a fee for an agent services account?

No. HMRC says registration is free and online.

Sources

Rates, thresholds and rules in this guide were checked against HMRC and GOV.UK guidance on 6 November 2026. Tax rules change, so check the current position on GOV.UK or with a qualified adviser before acting. This guide is general information, not personal advice.