Based on which percentage the empoyee has elected on the Arizona A-4 form (and these rates changed on January 1, 2005), input that rate in PR-A in the field called "St" which represents the state exemption number. This is different than for most states. The number you input into this field should correspond to the percentage (e.g. 10, 19, 23, 25, 31 or 37) elected by the empoyee. The PR-B program will then take that number and divide it by 100 in computing the appropriate state income tax withholding.