The W-4 that you fill out for your employer determines how much of your paycheck gets withheld for federal income taxes. At the end of the day, your withholding won't affect the amount of taxes you owe. But if you have your employer withhold a little extra each paycheck, you can surprise yourself with a tax refund at the end of the year.
The W-4 offers three filing status options: single, married and married but withhold at higher single rate. If you're single, that leaves you with only one option. But, if you're married, you can squeeze out a little extra withholding by choosing married but withhold at the higher single rate. That's because the tax brackets for joint filers are larger than for single filers, so if your employer treats you as single for withholding purposes, more will be withheld than you actually owe in taxes.
The number of personal allowances you claim has a big impact on your withholding. Each allowance you claim reduces the amount of your income that's subject to withholding by the value of one personal exemption. For example, in 2012, each allowance claimed reduces your income subject to withholding by $3,800. However, just because you claim an allowance doesn't mean you actually owe less in taxes. To ensure a refund, claim fewer allowances on your W-4 than you're actually entitled.
If you have additional income outside of your job that isn't subject to withholding, you may need to request additional withholding if you want to get a refund when you file your taxes. For example, if you have income from dividends, selling stock or interest, income taxes won't be withheld from those payments. To get a refund, you need to have additional money withheld from your paycheck. On line 6 of your W-4, you can enter any additional amount that you want withheld. For example, if you think your other income will add $1,200 to your taxes and you get paid monthly, having an extra $100 withheld from your salary each pay period will cancel out the extra taxes.
While getting a refund is nice, it's not always the best idea. When you have too much withheld, you're basically making an interest-free loan to Uncle Sam. The money gets taken out of your paycheck, and the government holds it until you file your tax return, which can be several months later. If you have outstanding loans or a high credit card balance that charges you interest, you could pay down that debt rather than lending money to the federal government.
Based in the Kansas City area, Mike specializes in personal finance and business topics. He has been writing since 2009 and has been published by "Quicken," "TurboTax," and "The Motley Fool."