26 CFR 31.3402(h)(3)-1 - Withholding on basis of cumulative wages.
(a) In general. In the case of an employee who has in effect a request that the amount of tax to be withheld from his wages be computed on the basis of his cumulative wages, and whose wages since the beginning of the current calendar year have been paid with respect to the same category of payroll period (e.g., weekly or semimonthly), the employer may determine the amount of tax to be deducted and withheld upon a payment of wages made to the employee after December 31, 1969, by taking the following steps:
Step 1. Add the amount of the wages to be paid the employee for the payroll period to the total amount of wages paid by the employer to the employee during the calendar year.
Step 2. Divide the aggregate amount of wages computed in Step 1 by the number of payroll periods to which that amount relates.
Step 3. Compute the total amount of tax that would have been required to be deducted and withheld under section 3402(a) if the average amount of wages (as computed in Step 2) had been paid to the employee for the number of payroll periods to which the aggregate amount of wages (computed in Step 1) relates.
Step 4. Determine the excess, if any, of the amount of tax computed in Step 3 over the total amount of tax already deducted and withheld by the employer from wages paid to the employee during the calendar year.
(b) Employee's request and revocation of request. An employee's request that his employer withhold on the basis of his cumulative wages and a notice of revocation of such request shall be in writing and in such form as the employer may prescribe. An employee's request furnished to his employer pursuant to this section shall be effective, and may be acted upon by his employer, after the furnishing of such request and before a revocation thereof is effective. A revocation of such request may be made at any time by the employee furnishing his employer with a notice of revocation. The employer may give immediate effect to a revocation, but, in any event, a revocation shall be effective with respect to payments of wages made on or after the first “status determination date” (see section 3402(f)(3)(B)) which occurs at least 30 days after the date on which such notice is furnished.
(c) Requests due to increases or decreases in allowances. An employee may request pursuant to this section that his employer withhold on the basis of the employee's cumulative wages when the employee is entitled to claim an increased or decreased number of withholding allowances under § 31.3402(m)-1 during the estimation year (as defined in § 31.3402(m)-1(c)(1)).