Yes. First one due tomorrow, I believe. IRS.gov and print off the form to send in with it.
That's assuming, of course, that you (or your spouse, if filing jointly) don't have W-2 income that will cover your liability. If you do, you have the choice of increasing your tax deduction enough to cover your liability.
You can also apply IRS refund toward next year's taxes.
If you've already filed and chose not to do that, just send in extra next quarter.
Actually, if you're on social security, just fill out the form for them to deduct income tax from your social security payment. Then you'll never have to worry about the quarterly stuff.
I don't know the number off the form, but social security will mail you the form and you fill it in and mail it back and a couple months later the deductions begin.
How did the ACA have anything to do with your taxes?