This decision outlines the procedures under Article 63 of the VAT Implementing Regulations for correcting tax returns. If an error results in an underpayment, the taxable person must correct the return and notify the Authority within twenty days of discovery. For underpayments less than SAR 15,000, the correction can be made in the next return. If an error leads to an overpayment, the person may deduct the excess amount in a subsequent return. However, corrections for overpayments are prohibited after five years from the end of the relevant calendar year, ensuring timely and accurate tax reporting.