Before you lock away your tax info and return for the year, look at your refund or balance due. Are you happy with it? Do you consistently owe the IRS or your state? Are you getting a big refund every year? Or, are you going to lose a deduction or credit on your 2012 tax return? Then this is the time to make changes in your withholding.
First, talk to your preparer. I like to see a check stub(s) with year to date info. Based on the info from that meeting, change your W-4 with your employer. You can change your status (Married/Single), the number of exemptions, or have them take out a specific dollar amount from each check. Then check the next paycheck to see if the changes were made. And you might have to handle your Federal withholding differently than your state withholding, so look at that also.
Let's face it, it's easier to deal with a smaller paycheck than write a balance due check to Uncle Sam. Or better yet, give yourself a pay raise because you always get a big refund. The choice is yours.