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HMRC internal manual

VAT Cash Accounting Scheme Manual

Cash accounting scheme: Records and accounts: Credit notes and adjustments in the course of business

Adjustments to the VAT account are only appropriate where tax has already been accounted for on payments received or made for supplies.

No adjustment will be necessary where an increase or decrease in consideration is agreed before any payment is received or made; the cash accounter’s payment record will just show the revised amount paid.