Publication 15
taxmap/pubs/p15-010.htm#en_us_publink1000202364Your 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_publink1000202365When 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.
taxmap/pubs/p15-010.htm#en_us_publink1000202366When 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.