If the u201ccorrect amountu201d is your actual tax liability, then you look and see how much you owe u2022 or how much of a refund you are getting u2022 when you prepare your return in April. Until you can do that, youu2019re just estimating.If the u201ccorrect amountu201d is the amount that your employer is supposed to withhold based on your W-4, then you can assume that it is correct. Very few payrolls are done manually these days.