<prompt> Human: I owe the IRS about 3,500.00 in unpaid taxes from a few years ago. I currently get paid 2x month, and have decided that they way I am going to pay back the IRSAnd I will not be moved on this is to authorize additional witholdings of 150.00 from each check, and they can just get theirs next year when I file taxes. They will take the additional funds. Yes they will. Theyre the IRS. Anyway, my question is in the title. Are the additional withholdings that Ive authorized pre tax, or post tax?  <response>: Financially that isnt the best way to do it. Your balance wont change and you will continue to pay interest on the full balance until you file your taxes and they apply the overpayment. Instead, you should enter into a payment plan with them and they will take a set amount each month directly from your account. Then your balance will drop and so will your interest. 