Credit and debit notes: adjust GST liability via prescribed issuance and return declaration, subject to pass on restriction.

Suppliers must issue credit notes when invoice value or tax exceeds the correct amount, for returns, or deficiencies, and declare such credit notes in the monthly return (or by the September after year end or relevant annual return), with tax liability adjusted as prescribed; reduction is barred if the tax incidence and interest were passed on. Conversely, suppliers must issue debit notes (including supplementary invoices) where invoices understates tax or value, declare them in the month of issue, and adjust tax liability as prescribed.

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