What is one of the happiest days of the year? Holidays excluded, for many people it is the day they get their tax refund check. Yep, cold, hard cash they can spend anyway they want. Alas, this is a mistake.

If you are getting sizeable tax refund checks each year, you are making a mistake with the withholdings from your paycheck. The federal government does not pay interest on the amount you overpay in taxes. As a result, you are giving the government an interest free loan throughout each year. While the government certainly seems to need every buck it can get, you would probably prefer to use the money yourself.

If you are overpaying or underpaying taxes out of your paycheck during the year, you need to tweak your W-4 withholdings. W-4 simply refers to the tax withholding form related to your employment and is filed by your employer. You can change the number of withholding by simply asking your human resources department.

To figure out the correct W-4 amounts, you used to need calculators, abacuses, forms and a minor psychic ability. Alas, the friendly IRS has made things easier. You can now go to the IRS site and access an online system that will figure it out for you. Simply search for “W-4” withholdings on the site and fill out the form. Once you do, it will calculate the information and let you know the adjustments you should make.

To fill out the form, you need a few things. First, you should have your last paycheck stub on hand. Second, you need your tax return from the previous year. If you need to estimate various information during the process, you can do so as long as you use reasonable numbers. It is not a test.

Once complete, the IRS site should spit out information for your withholdings. You should print this and compare it to your current information. Doing so should let you know if you need to make any changes.