The law requires you to make quarterly estimated payments, and there can be penalties and interest if you don't make the payments on time. You don't "file" a separate quarterly tax return, you just make a payment. There is a worksheet you can use to figure out the estimated payment you owe, and it looks like a tax return in some ways, but you don't actually file it. All you have to do is make the payments on time. And these days, there are program like Quickbooks to help you estimate the correct payment amount.
You only file one tax return at the end of the year. If your estimated payments are more than you owe, you get a refund. If your estimated payments are less than your tax, you will owe an additional amount when you file.
If you have been making payments, that's all you need to do. If you have not been making payments, there can be penalties when you file your tax return, even if you pay in full when you file.
