Credit and debit notes regulate invoice corrections, requiring timely issuance and return disclosure to adjust tax liability. If a tax invoice overstates taxable value or tax, the supplier may issue a credit note; if it understates them, the supplier must issue a debit note. Such notes must contain prescribed particulars and be issued by the earlier of the thirtieth day of September following the end of the financial year of supply or the date of filing the relevant annual return. Notes are to be declared in the monthly return for the month of issue or receipt (or a subsequent month) subject to the same outer deadline, and tax liability shall be adjusted under the Act.