This discussion addresses how to handle missed sales invoices from the 2017-18 financial year. The consensus is to declare the actual transactions in your annual return and pay the outstanding tax liability, along with applicable interest, using the DRC-03 form. Calculations for interest are provided, typically at 18% per annum, starting from the day after the original due date (usually 1st April 2019 for FY 17-18 if not filed by 31st March 2019).