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Mtd client_or_agent_not_authorised


I have tried to submit my client’s VAT returns, but I have received error:
There was a problem submitting your VAT return
Hmrc Error Code: 403
Message: The client and/or agent is not authorised.

I have submitted VAT returns from different software and I am definitely authorised as an agent, I have also checked my client registration and on HMRC website on my account it showed message:
Your client has already signed up
This client’s details are already in use.

Could anyone help me please?
Thanks, Ewa

Hello @EWAcc

The error message is returned to us by HMRC, rather than being generated by us.

Has the client registered for MTD and authorised your ASA to submit on their behalf? If you log into your ASA directly with HMRC, do you see their account there?

Hello Matthew,

Thank you for a quick response.

Client registered for MTD 2 months ago and then authorised me to submit on their behalf - but only today. Do you think I need to wait longer to be able to submit VAT return?

I cannot see my client on my MTD account (I cannot see any of my clients, only when I want to do something I input their VAT number and their data suddenly appears), but when I tried to sign him up again, because I wanted to check what is the problem, the message I received was:
Your client has already signed up
This client’s details are already in use.


This may need a while to process, although I can’t confirm as it’s on HMRC’s side of things.

One thing I do want to check however, is how are you trying to submit this? If it’s an ASA (agent account), are you doing it via your Affinity account?


I have tried to submit it again today, but unfortunately the same message came up.

I have connected client via my new MTD agent account.

Any clues what should I do now? Shall I contact HMRC and see what do they have got on their end?

Thanks, Ewa

Hi @EWAcc,

It may be worth logging into your HMRC account directly to make sure the link is there, but you may need to contact HMRC to confirm.

Sorry we couldn’t be more help

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