(1) If an employer does not pay to the Board any amount of unpaid accumulation or fine realised from an employee or the amount of employer's or employee's contributions under section 9, within the due time the Welfare Commissioner may cause to be served a notice on such employer to pay the amount within such time as may be mentioned in the notice.
(2) If the employer fails without sufficient cause to pay such amount within the period specified in the notice, he shall, in addition to that amount, pay to the Board simple interest—
(a) for the first three months at one per cent. of the said amount for each complete month after the last date by which he should have paid it according to the notice, and
(b) at one and half per cent. of that amount for each complete month thereafter:
Provided that the Welfare Commissioner may, subject to such conditions as may be prescribed, remit the whole or any part of penalty in respect of any period.