5Calculation of stake
The aggregate amount paid by or debited to the account of a person making a bet chargeable with general betting duty for, or on account of, or in connection with, the bet shall be treated for the purposes of that duty as his stake on the bet, notwithstanding—
(a)that his winnings (if any) are to be computed on part only of that amount, or
(b)that part of that amount is not to be returned to him in the event of his winning,
and no deduction shall be made for other benefits secured by the person making the bet in paying that amount, or for the expenses of any person on account of the duty or otherwise, or for any other matter.