I submit a changed W-4 to my employer to include additional withholdings. On today's paycheck, they withheld 3x that amount in additional withholdings. Their reasoning is that since I submit the change the same day as my last paycheck, " the system did retro entries for the taxes" (verbatim). How is that possible? I asked for clarification since I know retro deductions are not supposed to be allowed, and was advised that Federal is always prorated. They acknowledged that there is nowhere for me to see that information to have known it would happen. Are they allowed to do that? Where can I get more information on how changed W-4 works for deductions once applied? Nothing discusses retroactive deductions clearly.
