To pay tax on an amount which is not part of the gross pay, as might be the case with alimony,
Enter the amount on which tax is to be paid as a pre-tax adjustment. A separate Pay Item should be created for this purpose.
Calculate the payroll in full, ensuring the employee paying the tax is included.
Next, remove the pre-tax Pay Item adjustment. Kindly note recalculating the payroll will remove the tax amount and the process would have to be repeated.