The Internal Revenue Service, or IRS, collects taxes every year, primarily money withheld from your salary or other income as it’s being paid.

You’ll fill out a W-4 form whenever you begin working for an employer full- or part-time. This form determines how much money is withheld from each paycheck in order to cover the taxes you’ll owe for the year.

No later than the end of January, your employer will send you a W-2 form, which reports the money you’ve earned for the previous year, the amount withheld for income taxes, Social Security, Medicare, and any additional deductions. Or, if you’re a freelancer, you’ll receive a 1099 form from each employer, reporting the amount of money you were paid for the work you did. If you’re investing or saving, you’ll get a 1099 from each financial institution where you have an account, too. If no taxes are withheld, you may have to pay estimated taxes.

Calculate your taxable income using four steps. Click here to learn more!

By every April 15, you must compare the total amount in taxes you owe against the total amount of money withheld from your salary during the year or paid in estimated taxes. Depending on how these figures compare, you either owe the IRS the difference, or receive a refund for any excess withheld during the year.