Is it possible to modify VAT period to 4 monthly, something happened ON HMRC and changed period to Jan-Apr that will be followed to May-June and then quarterly as normal?

Hello sales50,

Welcome to the Community - thank you for your question!

When you are ready to file that period, select 'submit return' and change the end date to what you need it to be. The next return that opens will then follow the usual quarterly dates.

Thanks,

Talia