Self Assessment tax returns – agents using the ‘file only’ service

1. It is possible for agents to file Self Assessment tax returns on behalf of people who have not signed form 64-8 to authorise the agent to act on their behalf. This can be done using commercial software packages only – it is not possible for an agent to file a tax return for so-called 'unauthorised clients' using HM Revenue & Customs (HMRC's) software. Apart from receiving electronic confirmation that the tax return has been accepted, the agent will receive no other correspondence from HMRC for unauthorised clients.

2. Tax returns filed electronically using commercial software are submitted via the Government Gateway. Most of the validation checks aren’t done until the tax return reaches HMRC’s systems but the Government Gateway will perform some basic authentication including:

User ID
password
UTR (Unique Taxpayer Reference)

The User ID and the password must correspond in all cases. The UTR will be validated against an agent’s ‘Authorised Client List’. For ‘File Only’ cases, the Government Gateway recognises that the tax return is being filed by an agent (determined by the User ID) and if it can’t match the UTR to the ‘Authorised Client List’ then it will simply check that the UTR is genuine.

3. Before anyone can file a tax return on someone else’s behalf (ie as an agent) and irrespective of whether the other person has authorised the agent to act on his or her behalf, the agent must both register as an agent with the Government Gateway and enrol to use Self Assessment. This can be done either directly at the Government Gateway (this will take you to the homepage, where you should then click on <Register as an ‘Agent’> on the right hand side of the screen) or (recommended) via HMRC's website.

4. The Registration and enrolment process can only be completed if the agent has first obtained an Agent ID from HMRC. This is a 6-character ID, which starts and ends with a letter, with four numbers in between. The Agent ID will be posted to the agent when s/he has told HMRC that s/he wants to become an agent.

5. The agent will choose his/her own password, whether s/he registers directly at the Government Gateway or via HMRC’s website. The password, in either case, must be between 8 and 12 characters and include at least one number (0-9) and at least one letter (a-z).

6. The User ID for the Government Gateway will be generated automatically – it will comprise twelve numeric characters. It is this User ID that corresponds with the password.

7. Separately, there is a Gateway Agent Identifier. It comprises twelve alphanumeric characters and is generated automatically if registering via HMRC’s website. If registering directly at the Government Gateway then the agent will choose the first half of the Gateway Agent Identifier (actually called the 'Agent ID' by the Government Gateway), with the second half generated automatically. The agent can choose between 1 and 12 characters, letters or numbers, but must not include either spaces or punctuation. The auto-generated part of the Agent ID will comprise twelve alphanumeric characters.

8. A separate Activation PIN will be generated for each service the agent enrols for. They will be posted to the agent from the Government Gateway, who then has to access online services using his/her User ID and password to key in the Activation PIN to complete the Registration and enrolment process. Assuming the agent has enrolled to use Self Assessment Online then s/he will now be able to file tax returns for other people.

9. An agent must use an Internet-enabled commercial software package to be able to file a return for 'unauthorised clients'. It is not possible to provide generic guidance on how an agent would complete and submit a tax return electronically via the Internet, because software packages will adopt different approaches but at some point in the process for creating and submitting a tax return, the ‘file’ that is sent to the Government Gateway must include the agent’s User ID (not the Agent ID/Gateway Agent Identifier), the agent’s password and the client’s UTR.

10. Glossary of terms

User ID - A 12-digit number, generated automatically either by the Government Gateway or on HMRC’s website, that’s used to access online services.
Password - Comprises 8-12 characters, which the user can choose, and must include at least one letter (a-z) and at least one digit (0-9) and cannot include the word 'password'. The password is used in conjunction with the User ID to access online services.
Activation PIN - Each online service (eg Self Assessment or PAYE) will have a separate Activation PIN. They are generated and posted by the Government Gateway for each service that a user enrols. The user then has 28 days (from the date on the letter) to activate each service before the Activation PIN expires. Once the service has been activated the Activation PIN can be destroyed; it won’t be needed again.
Agent Reference Code/Number - These identifiers, 'codes' and 'numbers' are both valid terms, have a wider application than just online services. They are the identifiers that HMRC uses to authenticate the agent. There is a different code for each type of tax (Self Assessment, Corporation Tax, PAYE, etc) and they’re needed to enrol for the corresponding online service.
Agent ID – This is a Government Gateway term. It serves the same purpose as the 'Gateway Agent Identifier', see below. If an agent registers and enrols directly at the Government Gateway then s/he can choose the first ‘half’ of the Agent ID, between 1 and 12 alphanumeric characters. The Government Gateway then generates the other ‘half’ of the Agent ID – it will be 12 alphanumeric characters, so the Agent ID could be between 13 and 24 characters in length. The Agent ID is not used to access online services. It’s used by an agent’s VAT clients if those clients want to authorise the agent to act on their behalf for VAT. It does not have a corresponding password associated with it.
Gateway Agent Identifier - This is an HMRC term. It’s used by an agent’s VAT clients to enable them to authorise the agent to act for them, like the 'Agent ID' - see above. The Gateway Agent Identifier comprises exactly 12 alphanumeric characters and it is generated automatically by HMRC; the agent is not given the choice to choose part of the identifier as s/he would be when generating an Agent ID on the Government Gateway. Again, it is not used to access online services and it does not have a corresponding password associated with it.