Invoice received on after vAT declaration

Invoices can always be entered in a later quarter. I would not reopen an open quarter in dexxter (or any accounting programme), as this is really something for advanced users. You will then have to manually correct your vAT declaration. If you do decide to do this, always make a print from your diaries on which you note the changes. I advise you to remove those invoices back and simply enter them in the next quarter.