(1) Subject to subsection (2), regulations may provide for the determination of the contributions payable, the amount or rates of such contributions, and the contribution weeks in respect of which such contributions shall be regarded as having been paid, in the case of a person who -
(a) becomes for the first time a self-employed contributor,
(b) ceases to be a self-employed contributor,
(c) is both an employed contributor and a self-employed contributor whether concurrently or not,
(d) in any contribution year has reckonable emoluments but does not have reckonable income,
(e) in any contribution year has both reckonable emoluments and reckonable income, or
(f) in any contribution year has reckonable emoluments which relate to a period less than the full year.
(2) Regulations made under subsection (1) shall not cause an insured person to pay contributions on the excess over the amount specified in section 18(1)(d) of the aggregate of his total reckonable earnings, reckonable emolu