Regulations may provide for -
(a) the determination of optional contributions payable, the amount or rates of those contributions, and the contribution weeks in respect of which those contributions shall be regarded as having been paid, in the case of a person who -
(i) becomes for the first time an optional contributor,
(ii) ceases to be an optional contributor, or
(iii) in any contribution year has reckonable earnings and reckonable income,
and
(b) any matter ancillary or incidental to any of the matters referred to in paragraph (a).