How to resolve CLIENT_OR_AGENT_NOT_AUTHORISED>?MTD is enabled (has been for a while)Connected to HMRCPreviously no issues.

Thank you, Rolf, for taking the time to troubleshoot the error you ran into when using MTD in QuickBooks Online (QBO) to handle VAT. I understand how challenging it can be when MTD errors persist even after reconnecting to HMRC and verifying your VAT settings. Let's take a few additional steps to resolve this problem.

The CLIENT_OR_AGENT_NOTAUTHORISED error happens when QBO isn’t authorised to connect to HMRC or the credentials are wrong. Since you’ve already reconnected and confirmed your VAT number, make sure you’re using login details specific to MTD instead of general Government Gateway credentials.

If the issue persists, I recommend contacting our Live Support team. They have the expertise and resources to uncover its root cause and provide the most effective solution.

Here's how:

1. Click (?) Help, then go to the Search tab.
2. Use the search field or open an article.
3. Select Contact Us at the bottom of the Help panel.
4. Enter your concern in the designated box and hit Continue.
5. Choose how you want to talk with an expert: Chat or Callback.

As you initiate the process above, please also ensure to observe their support hours.

For all of your QuickBooks Online needs, my team and I are just a message away. Reach out to us here if you need any more help with MTD or VAT submissions; we are always happy to assist. We'll make sure you're supported at every turn because you've already accomplished so much.