Hello, AndyGL.
It could be that the information we used is not authorised to use. First, let's make sure to enter the correct VAT registration number in the settings and login credentials. Check this article for additional reference: Take action to complete your Making Tax Digital (MTD) submission our Making Tax Digital (MTD) submis....
If you've done everything and already verified that information you entered is all correct, we can perform some troubleshooting steps to isolate why you're unable to connect to HMRC. Let's access your QuickBooks account using an incognito window. Here are the shortcut keys depending on the browser you're using:
- Google Chrome: Ctrl + Shift + N
- Microsoft Edge: Ctrl + Shift + P
- Firefox: Ctrl + Shift + P
- Safari: Command + Shift + N
If it works, let's go back to your main browser and clear the cache. A piled cache can also be the reason for the unexpected issues on the pages we've opened like QuickBooks. If it persists, you can use other compatible browsers.
I've added this article on how to connect to HMRC to submit VAT:
If there's anything else that I can help you with, please let me know in the comments. Stay safe!
