(1) If supplemental wages, such as bonuses, commissions, or overtime pay, are paid at the same time as regular wages, the state income tax to be withheld should be determined as if the total of the supplemental and the regular wages were a single wage payment for the regular payroll period.

(2) If the supplemental wages are paid at a different time, the employer may determine the state income tax to be withheld by adding the supplemental wages either to the regular wages for the current payroll period or to the regular wages for the last preceding payroll period within the same calendar year.

(3) In lieu of the above, the employer may withhold on supplemental wages at the rate of 6%.