Tying the knot requires a lot of paperwork, even where you wouldn't expect it. In addition to the paperwork to get your marriage license, your name changed and Social Security cards updated, you'll also have to update your W-4s for your employers. Not updating your W-4s with each of your employers could lead to inaccurate withholding from your paychecks.
Updating Filing Status
One of the factors used by your employer to determine how much to withhold is your filing status as specified on your W-4. Once you get married, you can have taxes withheld at the lower married rate. This is true because the federal tax brackets are larger for couples, so you usually won't owe as much in taxes after you tie the knot than you did when you and your spouse filed single returns. If you don't change your withholding, you'll end up with too much withheld so you'll get a larger refund when you file your return.
New Allowances Worksheet
If both you and your spouse work, you need to figure your allowances using the Two-Earners/Multiple Jobs Worksheet rather than the Personal Allowances Worksheet. Having multiple jobs makes withholding accurately harder because your employers don't communicate with each other. Therefore, you and your spouse need to sit down and complete the worksheet together and then have the spouse with the higher paying job report all of the allowances to make your withholding as accurate as possible.
Making Changes
Your employer has to let you change your W-4 whenever you want, so if you've gotten married and haven't updated, it's time to get on it. All you have to do is fill out a new W-4 and give it to your human resources department. Once you've turned it in, your employer has to start using it to figure your withholding by the beginning of the first pay period ending 30 days or more after you submit it.
Net Effects
Overall, your tax withholding should go down as a result of getting hitched because your overall tax liability will go down. However, the tax withholding for the spouse with the lower paying job may increase since all the allowances are shifted to the spouse with the higher paying job. If you don't update your W-4 after the wedding, your employers will continue to withhold at the higher rate. You'll still get the extra money back when you file your return, but there's no reason to make an interest-free loan to Uncle Sam when you've got things to do with the money.
