Thank you for bringing this to our attention, info2071.
The CLIENT_OR_AGENT_NOT_AUTHORISED error indicates that the credentials for connecting QuickBooks Online (QBO) to HMRC for MTD are not authorized to retrieve information or perform a VAT filing for the VAT Registration number in the VAT settings. These are some of the potential causes:
- Every 18 months you're are required by HMRC to re-establish your connection with them in QuickBooks. Try disconnecting and reconnecting your account to fix this.
- Using incorrect Government Gateway credentials or Agent Service Account (ASA) credentials.
- The VAT registration number in QBO might not match the one on file with HMRC.
You need to re-establish your connection with HMRC in QuickBooks every 18 months. You'll have to disconnect and reconnect to MTD to rectify the issue.
Also, utilise the MTD credentials given to you by HMRC. Make sure that the VAT registration number and the VAT accounting period you enter in QuickBooks match the ones you use for your VAT obligations with HMRC.
Refer to this article for detailed instructions: Take action and fix MTD issues and errors in QuickBooks Online. From there, proceed directly to the following section: Error "CLIENT_OR_AGENT_NOT_AUTHORISED".
After performing these steps, submit your MTD. Visit this article for guidance on how to correct your VAT: Make VAT adjustments in QuickBooks Online.
Drop a comment below if you have other VAT-related concerns or questions about managing your taxes and returns. The Community is available round the clock to provide the help you need.
