The amount of gift aid supplement that a charity is entitled to be paid in respect of a gift aid donation is—

$\mathrm{DGN}-\mathrm{DGA}$

where—

DGN is the amount of the gift aid donation grossed up by reference to the notional basic rate for the transitional tax year, and

DGA the amount of the gift aid donation grossed up by reference to the actual basic rate of income tax for the transitional tax year.

A charity is not entitled to be paid gift aid supplement in respect of a gift aid donation if the amount determined in accordance with sub-paragraph (1) is a negative amount.