Thanks for visiting to the Community, Riki Shinozuka,
Let me help share information in submitting VAT returns to HMRC.
In order to file VAT return to HMRC, make sure to use the login credentials for submitting payroll.
To get this be fix, we can perform some basic troubleshooting steps like using an incognito/private browser.
Just follow the keyboard shortcuts below to open a private browser:
- Google Chrome: press Ctrl + Shift + N
- Mozilla Firefox: press Ctrl + Shift + P
- Internet Explorer: press Ctrl + Shift + P
- Safari: press Command + Shift +N
Once able to open a private browser, try to submit VAT return again.
I'd appreciate if you can update me on how it goes. I'll be here if there's anything else you need about QuickBooks Online. I'm wishing you continued success.