TAXATION (INTEREST ON OVERPAYMENTS AND EARLY PAYMENTS) ACT 1983
Subject to subsection (2), interest under section 8A is payable to a person for the period:
(a) if the person is not a full self-assessment taxpayer - from the beginning of the later of the following days:
(i) the day on which the payment is made;
(ii) the day on which the notice notifying the tax, debt, interest or instalment concerned is issued; and
(b) if the person is a full self-assessment taxpayer - from the beginning of the day on which the payment is made;
until the end of the appropriate due day.
If the payment is to any extent refunded before the appropriate due day, interest is not payable on the payment to that extent in respect of any period after the day on which the refund takes place.