Credit and debit notes require dealers to issue corrective notes when invoice tax differs from payable tax. Where a tax invoice has been issued, a dealer must provide the purchaser with a credit note if the tax shown in the invoice exceeds the tax payable, or a debit note if the tax payable exceeds the tax shown; each note must contain such particulars as may be prescribed, subject to sub-sections (1) and (2) of section 8.