Your wedding present from Uncle Sam may be higher taxes, known as the marriage tax penalty. This is a scenario when you pay more in taxes because you are “married filing jointly.” If both of you make $65,000 per year, you might pay more as a married couple than you would as singles, even though you're talking about $130,000 of income either way.

The problem used to be much worse, but Congress has taken action to reduce the penalty. However, laws come and go and the marriage penalty is no exception. In 2007, couples were penalized as they got higher and higher along the income spectrum. The couple above (each making $65,000 per year) would suffer only a modest penalty. In previous years, the marriage tax penalty started at lower income levels.

In general, couples are penalized if they both earn a similar amount of money. Couples may benefit if their income levels are very different — for example, one partner might not work, or one partner might have an extremely high salary. The often-ignored flip side of the marriage tax penalty is the marriage tax “bonus.” Besides higher taxes, you could get a rude jolt when you prepare your income tax return. If you both checked “married” on your new W-4 at work, your payroll departments will calculate withholding based on the standard deduction for married individuals. You'll have taxes withheld as though you were entitled to twice the standard deduction and your taxes will be underwithheld significantly. To prevent this from happening, after you get married you should file new W-4s with your respective employers with one of you checking the married status and the other checking the single status. This will help correct your withholding so you're not hit with a huge tax bill in April. You can also use the IRS's withholding calculator at www.irs.gov to figure out exactly how you should set up your withholding.