(1) Where payments are made to a person on account of remuneration in two or more employments under the same employer which include both an employment which is, and an employment which is not, at the time of payment in respect thereof a non-participating employment, and, under section 4(3)(a) of the National Insurance Act 1965, those payments fall to be aggregated and treated as a single payment of remuneration in one employment, that one employment shall, for the purposes of the said section 4(3)(a), be taken to be—
(a) an employment which is at the time of the payment a non-participating employment, if at the time of the payment (or each payment if there is more than one) in respect of participating employment which falls to be aggregated the person is employed in a non-participating employment under that employer; and
(b) subject to the provisions of paragraph (2A) of this regulation, in any other case an employment which is at the time of the payment a participating employment;
and for the purposes of this Part of these regulations a “ participating employment ” means an employment which is not a non-participating employment.
(2) Subject to the provisions of paragraph (2B) of this regulation and without prejudice to the provisions of section 4(5) of the National Insurance Act 1965 as to the disregarding of payments of remuneration, where a payment on account of a person's remuneration in a participating employment is made at a time when he is employed in a non-participating employment under the same employer, then, if that payment does not fall to be aggregated under section 4(3)(a) of that Act with a payment of remuneration from the other employment, the payment shall, for the purpose of graduated contributions, be treated as a payment on account of remuneration in an employment which is at the time of the payment a non-participating employment.
(2A) Where a payment (hereafter in this paragraph called “ the payment in question ”) on account of a person's remuneration in a participating employment is made at a time when that employment and his employment in a non-participating employment under the same employer have both come to an end, then, if the last payment made on account of his remuneration in that participating employment before that participating employment came to an end fell (or would but for its being made before 5th October 1966 have fallen) under the provisions of paragraph (1) or paragraph (2) of this regulation to be treated as a payment on account or remuneration in an employment which was at the time of the payment a non-participating employment, the said provisions shall apply as if the payment in question had been made at a time when the said person was employed in the non-participating employment under that employer.
(2B) The provisions of paragraph (2) of this regulation shall not apply in a case where, having regard to the arrangements which are or might reasonably be made for the calculation and payment of the remuneration, it is not reasonably practicable at or before the time of the payment for any of the persons calculating or making the payment to have such information about the other employment as would enable them to know whether the provisions in question were applicable.
(3) For the purpose ... of this regulation, at the time of a payment on account of his remuneration in a participating employment a person shall be deemed not to be employed in a non-participating employment if—
(a) his employer is not and has not been liable to pay weekly employer's contributions in respect of that non-participating employment for the contribution week in which that payment is made and for the thirteen contribution weeks immediately preceding, and his failure to be so liable does not arise by virtue of the provisions of subsection (1) of section 4, or of any regulations made under paragraph (a) of subsection (1) of section 9, of the Act (which provide respectively that not more than one employer's contribution shall be payable in respect of any person for any week and as to the persons who are to be treated as employers); or
(b) that payment is made in a contribution week for which his employer is not liable as aforesaid, being part of a continuous period which is to last thirteen weeks or more for which he will not be so liable and for which his failure to be so liable does not arise by reason of that person's being, in those weeks, incapable of work or by virtue of the said provisions or of any such regulations.
(4) In this regulation “ "remuneration” ” has the same meaning as in the Act of 1959.