How to use the Self Assessment for Agents online service

This guide explains how to sign up for and use the HM Revenue & Customs (HMRC) Self Assessment for Agents Online Service.

You can use the service to set up authorisations for Self Assessment, send tax returns and view statements online.

On this page:

HMRC's Self Assessment for Agents online service - an overview

HMRC's Self Assessment for Agents online service allows you to carry out many tasks online on behalf of your clients. It is safe, secure and reliable. You must sign up for this service whether you plan to use HMRC Online Services or commercial software to send your clients' tax returns.

What you can do online with Self Assessment for Agents

You can use the online service to:

  • send your clients' Self Assessment tax returns over the internet - with or without attachments
  • view your Self Assessment clients’ PAYE Coding Notices
  • view their statements online
  • view their tax liabilities and the payments they've made
  • make claims to reduce their payments on account
  • view and change your clients' contact details online
  • access the secure email service to send questions to HMRC and get replies

See a demonstration of the Self Assessment for Agents online service

Benefits of using Self Assessment for Agents

Using the online service offers a number of benefits over sending paper returns, including:

  • automatic calculations - helping to reduce mistakes
  • immediate confirmation that HMRC has received the tax return
  • faster processing of tax returns and repayments (depending on security checks)
  • the ability to part-complete a return and finish it at a later date
  • a secure email service for sending queries and receiving replies

Deadlines for paper and online tax returns

If you wish to send a paper tax return on behalf of your clients, generally it must reach HMRC by midnight on 31 October.

If you send it online, you get longer - the deadline for submitting your tax return is midnight on 31 January.

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Signing up for Self Assessment for Agents

If you've not already registered as an agent for Self Assessment and wish to act on your clients' behalf for Self Assessment matters, you need to write to HMRC to do so. You'll then receive a Self Assessment agent code which you'll need before you can set up the online service.

How to obtain an agent code for Self Assessment

Once you have your Self Assessment agent code, there are two ways of signing up for the online service.

If you're already using HMRC Online Services for agents

You should log in to HMRC Online Services and add the Self Assessment for Agents service to your portfolio from the 'Services you can add' section of 'Your HMRC services'.

Log in to HMRC Online Services

If you're a new user

You need to register for HMRC Online Services then enrol for the Self Assessment for Agents online service by following the steps below:

  1. Go to the HMRC homepage and select 'Register (new users)' under the 'Do it online' section.
  2. Follow the link to 'Sign up for HMRC Online Services' in the section 'When to sign up for HMRC Online Services separately'.
  3. Select the 'Agent' option and follow the on-screen instructions to enrol for Self Assessment for Agents.

How the registration process works

The registration process only takes a few minutes to complete. You'll have to:

  • provide your Self Assessment agent code and postcode
  • create a password
  • make a note of your on-screen User ID and keep it safe - it will not be displayed again
  • make a note of your 'Gateway Agent Identifier' - you'll need this if you want to act online on your clients' behalf

HMRC will send you an Activation Code by post within seven days of registering for Self Assessment for Agents. You must activate the service within 28 days of the date on the letter otherwise you'll have to start this process again.

Register as a new agent user through HMRC Online Services

Activation Code not received, lost, or expired?

If you have your User ID and password but you have not received your Activation Code within 28 days of registration, you should check with the Online Services Helpdesk to ensure that HMRC has your correct address and postcode.

Contact the Online Services Helpdesk

If the Activation Code has been lost or has expired, you can request a new code online through the Government Gateway website.

Read more about lost or expired Activation Codes

Go to the Government Gateway website (Opens new window)

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Online agent authorisation for Self Assessment

Once you've signed up for Self Assessment for Agents you need to go through the client authorisation process for each client. When you've been through this process, HMRC can deal with you online, by phone or in writing about each of your clients' Self Assessment matters.

To submit an online authorisation request for your client you'll need:

  • to have registered for HMRC Online Services and enrolled for the Self Assessment for Agents service (see the section above to find out how to do this)
  • your client's Unique Taxpayer Reference (UTR) and postcode
  • the authorisation code HMRC will send to your client - this code begins with 'SA' - you'll need it to complete the authorisation process

Please note: the authorisation code can take up to seven days to arrive. You will need to enter the code before the client will appear on your client list, so ideally you need to do this well in advance of their tax return deadline. You must enter the code within 30 days from the date on the letter, otherwise it will expire.

Get client authorisation using HMRC Online Services

View a demonstration of client authorisation and management

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Viewing PAYE Coding Notices

You can view your Self Assessment clients' PAYE Coding Notices online if certain conditions apply. But first, you must register for HMRC Online Services and enrol and activate the Self Assessment for Agents online service (see previous sections for more information).

You will then be able to view PAYE Coding Notices online if both the following conditions apply:

  • the PAYE Coding Notice was issued on or after 11 October 2011
  • you were authorised to act on behalf of the client for Self Assessment (form 64-8 or online agent authorisation was in place) at the time the notice was issued

But please note: if your client previously had an agent who was registered for the Self Assessment for Agents online service, or if your client was registered for the service in their own right at the time the Coding Notice was issued, you may be able to view any notices issued on or after 11 October 2011, even if you became their authorised agent at a later date.

In due course, you'll be able to view PAYE Coding Notices - issued on or after 11 October 2011 - for the:

  • current tax year
  • previous tax year
  • next tax year

Generally, Coding Notices will be available to view online 72 hours after they are issued.

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Viewing liabilities and payments

Once you're authorised to act on behalf of your client, you can view their statements, tax liabilities and payments online.

You can also view and download your full client list.

See a demonstration of Self Assessment for Agents online service

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Sending online tax returns for your client

When you send your client's tax return online using Self Assessment for Agents you can use either:

  • HMRC's free online service
  • commercial software

Using HMRC's Self Assessment online service

You can use HMRC's online service to send the main Self Assessment tax return - form SA100 - and most supplementary pages. The online service checks the return as you fill it in and does the tax calculations for you.

You can also get free technical support from the Online Services Helpdesk.

Contact the Online Services Helpdesk

Using commercial software

You can use commercial software to send your client's tax return online. Commercial software also allows you to file the partnership return (form SA800) and the trust return (form SA900) as well as other Self Assessment forms.

HMRC provides a list of commercial software suppliers whose software has been tested to make sure it's compatible with HMRC's systems.

Find out about Self Assessment Online and commercial software

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Online administrators and assistants

The first person to set up your HMRC online agent account is called an 'administrator' for online service purposes. The administrator can appoint other administrators and/or assistants to help you manage your clients' Self Assessment matters online. This is a useful facility if you want to allocate specific clients to different people in your organisation. You set up administrators and assistants on the Government Gateway website.

Read more about how to manage users and assistants

Log in to your Government Gateway account (Opens new window)

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More useful links

Find practical advice to help you manage Self Assessment for your clients (Opens new window)

How to register your client's business with HMRC

File a tax return online (Opens new window)

What counts as reasonable excuse when an online tax return is filed late

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