56.4. A worker’s salary and wages on which a second additional contribution has been made for a year is equal to the amount obtained by dividing, by one-half of the second additional contribution rate for the year, the amount by which the aggregate of the following amounts exceeds the amount described in the second paragraph:(a) the aggregate of the deductions at source from the worker’s salary and wages for the year on account of the second additional contribution under this Act or a similar plan;
(b) any amount that an employer has not deducted at source from the worker’s salary and wages for the year on account of the second additional contribution, as the employer should have done under this Act or a similar plan, provided that the worker has given notice of that fact to the Minister on or before 30 April of the following year; and
(c) the aggregate of the amounts established under subparagraph b of the second paragraph of section 56 and subparagraph b of the second paragraph of section 56.2.
The amount to which the first paragraph refers is equal to the aggregate of(a) an amount equal to the product of the second additional contribution rate for employees for the year under the similar plan and the amount of the worker’s salary and wages on which a second additional contribution has been made for the year under the plan; and
(b) the excess amount established under the first paragraph of section 51.