A corporation filed its Annual Income Tax Return for the taxable year 2018 on April 15, 2019 together with its required attachments such as the Audited Annual Financial Statements. On March 17, 2020, the company's accountant discovered an error for excluding a sales amounting to 7,500,000 which comprises a 30% under declaration of sales. a. What necessary action must be done by the company in relation to its discovery? b. Assume that the company was subjected to a BIR audit or was issued a Letter of Authority (LOA) prior to the amendment of its Annual Income Tax Return, is the company allowed to make any amendment? Justify your answer