Thanks for reaching out to the Community forum, pwhiteelectrics.
In QuickBooks Online, once a VAT returns are due you'll receive a notification on the Dashboard page. To check, I recommend visiting your Dashboard page for the tasks that you'll need to accomplish.
That's it! This will point you in the right direction, pwhiteelectrics.
For future help, you can visit this article: Submit a VAT return in QuickBooks.
You can always get back to me if you have any other follow up questions. I'm always here to offer additional assistance. Have a wonderful day ahead.
