Self Assessment for Agents: HMRC online services

How to get an agent code, register with HMRC online services and set up agent authorisation for the Self Assessment for Agents online service.


The Self Assessment for Agents Online Service covers individuals, businesses, trusts and partnerships. Client authorisations also cover National Insurance and, for individuals, requests for information to help calculate the High Income Child Benefit charge.

To use the Self Assessment for Agents Online Service you’ll need to:

  • have an agent code
  • be registered with HMRC’s Online Services
  • add the Self Assessment for Agents service to your portfolio
  • set up agent authorisation for each of your clients

You must register for the Self Assessment for Agents Online Service whether you plan to use HMRC online services or commercial software to send your clients’ tax returns.

How to get an agent code

Before you can set up agent authorisation you must have an agent code. To get a code you need to register as an agent for Self Assessment in writing.

You’ll have to give the following information in your application:

  • full name
  • trading name (if different)
  • address that your activities are carried out from (this cannot be a PO Box address)
  • telephone number
  • email address
  • supervisor for the purposes of The Money Laundering Terrorist Financing and Transfer of Funds Regulation 2017 - details of Professional Body membership or Anti Money Laundering Supervision registration number
  • Self Assessment or company Unique Taxpayer Reference (UTR) number
  • details of which taxes you plan to deal with as you may need a separate agent code for each tax

Your application will be rejected if you do not give this information, or if HMRC is not satisfied with the information you provide. HMRC will tell you if your application has been successful within 28 days and send you a Self Assessment agent code to set up your online service.

HMRC online services

If you already use HMRC online services you can add the Self Assessment for Agents service by signing in and adding the service to your portfolio from the ‘Services you can add’ section of ‘Your HMRC services’.

If you do not have an HMRC online services account you’ll need to register as a new user through the service.

You’ll have to:

  • 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
  • wait for an activation code to arrive in the post before you complete your registration

Activation code not received, lost, or expired

If you do not receive an activation code within 28 days of registration contact the Online Services Helpdesk to check HMRC has the correct address for you.

If your activation code is lost or expired, sign in and request a new one by following the ‘activate’ link under ‘action’.

Set up agent authorisation through the Self Assessment for Agents service

Once you’ve added the Self Assessment for Agents service to your portfolio you’ll have to get agent authorisation for any new or previously unauthorised clients. Log into the service and follow the instructions under ‘Request an authorisation’.

You’ll need:

  • your client’s UTR
  • your client’s postcode
  • the authorisation code HMRC send to your client by post - this code begins with ‘SA’ and you’ll need it to complete the authorisation process

The authorisation code can take up to 7 days to arrive. You’ll need to enter the code before the client will appear on your client list, so you need to do this in advance of their return filing deadline. You must enter the code within 30 days from the date on the letter otherwise your client will have to repeat the process.

Once this process is complete you’ll be able to see your client on your Self Assessment for Agents client list within a few days. HMRC can now deal with you online, by phone or in writing about each of your clients’ Self Assessment matters.

HMRC will now send letters and forms direct to you, including your clients Self Assessment statements (SA300) and any fixed automatic penalty notices (SA328). You’ll also be able to view your client’s account online along with any statements of account.

What you can do in the service

You can use the Self Assessment for Agents Online Service to:

  • view your Self Assessment client’s PAYE coding notice
  • view your client’s Self Assessment statements
  • view the tax liabilities and the payments a client has made
  • make claims to reduce your client’s payments on account
  • submit your client’s tax returns online
  • view and change your client’s contact details online
  • access the secure email service to send questions to HMRC and get replies
  • download your full client list

View PAYE Coding Notices

You can view your clients’ PAYE Coding Notices online if:

  • 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

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.

You’ll also be able to view PAYE Coding Notices for the:

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

Coding notices are usually available to view online 72 hours after they’re issued.

Send 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

How to use 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 complete it and does the tax calculations for you.

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

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 Self Assessment commercial software suppliers whose software has been tested to make sure it’s compatible with HMRC systems.

Commercial software for other HMRC online systems is also available.

Published 1 January 2014
Last updated 23 May 2018 + show all updates
  1. The regulation name in section 'How to get an agent code' has been updated to The Money Laundering Terrorist Financing and Transfer of Funds Regulations 2017.
  2. Agent online services guidance has been updated to improve style and layout of content. HMRC Online Services log in information also updated in this guide.
  3. First published.