"80(1) Where a person— (a) has accounted to the Commissioners for VAT for a prescribed accounting period (whenever ended), and (b) in doing so, has brought into account as output tax an amount that was not output tax due, the Commissioners shall be liable to credit the person with that amount … (2) The Commissioners shall only be liable to credit or repay an amount under this section on a claim being made for the purpose. (7) Except as provided by this section … the Commissioners shall not be liable to credit or repay any amount accounted for or paid to them by way of VAT that was not VAT due to them."
"a claim for the crediting or repayment of an amount under section 80 …"