G6.—(1) The employer of a person in pensionable employment is to pay to the Secretary of State, within 14 days after the end of each month—
(a)all amounts due from the person that are deductible from his salary under regulation C16(1), and
(b)the contributions payable under regulation G5,
in respect of his contributable salary for that month.
(2) For the purposes of paragraph (1)—
(a)all salaries are to be treated as being payable monthly in arrear, and
(b)any arrears payable by reason of a retrospective increase in contributable salary are to be treated as having become payable in the month in which they were paid.
(3) If the full amount of any payment required by paragraph (1) is not received by the Secretary of State within 14 days after the end of the month interest is payable by the employer on the amount outstanding at 12 per cent per annum, compounded with monthly rests, from the 15th day to the date of payment; but the Secretary of State may in any particular case waive the payment of interest.