You'll need to contact HMRC to verify the reason of the rejected submission. This will let us review and resubmit your VAT return in QuickBooks Online (QBO).
Let's also make sure you've set up the VAT settings correctly. Here are the steps:
Go to Taxes.
On the VAT page, click on the Edit Vat drop down and choose Edit Settings.
In the Edit Vat settings window, review and enter the correct all the information.
Click on Save once you're done.
Then, contact our QuickBooks Payroll Support since they have more tools to change the filing status and help resubmit your return.