Did they take withholding out of your paychecks? And you still owe $5,000 more? Does the withholding from W2 box 2 show up on 1040 line 25a? Do you have any other income that doesn't have withholding taken out like interest or investments? Did you have more than 1 job and get another W2?
Better give your employer a new W4 to have more taken out.
