51 Credit and debit notes

 Subject to sub-sections (1) and (2) of .section 8, where a tax invoice has been issued in respect of a sale and 

(a)  the amount shown as tax in that tax invoice exceeds the tax payable in respect of the sale, the dealer shall provide the purchaser with a credit note, containing such particulars as may be prescribed; or

(b) the tax payable in respect of the sale exceeds the amount shown as tax on the tax invoice, the dealer shall provide the purchaser with a debit note, containing such particulars as may be prescribed.