There are a couple situations when you should fill out a W-4 form. The most common are when starting a new job and when your tax situation changes (like a marriage, a new kid, or a kid no longer being claimed as a dependent on your tax return).

There are a couple ways to fill it out a W-4 form. (1) If your situation is simple, you can just fill out Steps 1 and 5 and call it good! (2) Or if your circumstances are more complex you can fill out Steps 2-4 as well (for example if you have multiple jobs; if both you and your spouse work; if you are claiming dependents; or if you have other self-employment, investment, or retirement income).

If you choose option 2, things can get a little complicated. Unless you’re a masochist and want to do the worksheets yourself, use an online calculator. The IRS provides one at irs.gov/w4app. Or there are others around that are a little easier to follow (like HRBlock’s at www.hrblock.com/w-4-calculator).

And as a general rule, if you want more tax withheld from your paychecks, you can reduce the number of dependents you put on the form, you can add an extra amount on line 4(c), or you can change your filing status from married or head of household to single (the info on your W-4 only affects your withholding numbers on your paycheck and doesn’t affect your tax return in any other way). If you want less money withheld, just do the opposite.