Use the default Bonus earnings type to add bonuses as a fixed dollar amount in a payroll run.
Withholding for Bonuses
Bonuses are considered supplemental earnings, and taxes may be calculated on bonus amounts at the flat supplemental rate of 22% if paid separately from regular wages in Zenefits Payroll.
If someone has regular earnings and supplementary earnings in the same paystub, Zenefits Payroll will withhold taxes from the combined amount based on the the W-4 information and annualized wages. The supplemental rate is only used for supplementary earnings paid in an off-cycle run, without regular wages.