When planning a wedding, the last thing on your mind, is Income Taxes. However if you get married by the 31st of December you are treated as married for the entire year. Your filing status can have a large effect on your taxes so keep that in mind when planning.
If you’re married at year-end, you have only two choices: (1) File jointly with your new spouse, or (2) Use married filing separate status for a separate return based on your income and your deductions and credits. Most married couples file jointly.
Filing jointly is easier because only one return will need to be filed and by filing jointly you and your spouse may still be eligible for credits such as the child care credit and education credits. When filing separately you run the risk of loosing credits and two returns will need to be filed making figuring deductions difficult. In some cases filing a separate return can decrease the overall tax liability but those returns are few and far between. Often filing jointly is the best option; however you should consult with your tax preparer to determine this for your situation. Even if the tax liability is decreased when filing jointly you may still want to weigh your options.
For any year that you file a joint return, you’re generally “jointly and severally liable” for any federal income tax underpayments and penalties caused by your new spouse’s unintentional tax errors or omissions or deliberate tax misdeeds. Joint and several liability means the IRS can come after you for tax underpayments and penalties if collecting from your spouse proves to be difficult or impossible. They can even come after you long after you’ve become divorced.
Source: smartmoney.com