If you're an employee, your employer withholds taxes from every paycheck and sends the money to the IRS, and probably to your state government as well. This way you pay your income taxes as you go. And, if you're like most wage earners, you get a nice refund at tax time. But if you are self-employed, or if you have income other than your salary, you may need to pay estimated taxes each quarter to square your tax bill with Uncle Sam. We'll make it easy for you to figure out if you have to pay estimated taxes and if so, how much.