First, I am 'assuming' when you say "Paycheck" that you are in deed an employee and NOT a subcontractor. Then, if that is true, you will have to pay it when you file your Federal Taxes at the end of the year; possibly with a penalty for not paying all along. (I would definately question the payroll department though (or the owner, if it is a small company) and make sure that you are an employee. Did they take out State taxes, Social Security, etc.? (Those answers are important but depend on what state you live in and what you do for a living; ie. If you work for... A school, they may not take out Soc. Sec.)