Your payroll period is a period of service for which you usually pay wages. When you have a regular payroll period, withhold income tax for that time period even if your employee does not work the full period.taxmap/pubs/p15-010.htm#en_us_publink1000202365
When you do not have a regular payroll period, withhold the tax as if you paid wages for a daily or miscellaneous payroll period. Figure the number of days (including Sundays and holidays) in the period covered by the wage payment. If the wages are unrelated to a specific length of time (for example, commissions paid on completion of a sale), count back the number of days from the payment period to the latest of:
- The last wage payment made during the same calendar year,
- The date employment began, if during the same calendar year, or
- January 1 of the same year.
When you pay an employee for a period of less than one week, and the employee signs a statement under penalties of perjury indicating he or she is not working for any other employer during the same week for wages subject to withholding, figure withholding based on a weekly payroll period. If the employee later begins to work for another employer for wages subject to withholding, the employee must notify you within 10 days. You then figure withholding based on the daily or miscellaneous period.