Let's say you're considering adjusting your contribution to your retirement fund. Knowing your adjusted gross income could help you decide how much to increase or decrease your contribution if you are trying to stay in a particular tax bracket. Or, maybe you're negotiating a raise with your employer. Knowing your AGI before you ask for more money can help you determine how much to ask for.
That said, you can calculate adjusted gross income using a W-2 if you have the right tax form that lists all possible income and expenses to offset your gross income. Your W-2 tells you how much you earned from an employer. If you have any other income, that will not be included on a W-2.
Look for the Wages
A W-2 has a lot of information in its boxes. You need to know your total gross wages for the year, and that is found in Box 1 - Wages, Tips and Other Compensation. The amount in this box represents what you earned from that employer during the previous year. If you have more than one W-2, total the amounts from that box on each W-2 to get your total income for the year.
Calculate Expenses and Adjustments
Now that you know how much you made for the entire year, tally your deductions and expenses. The easiest way to do this is by following the list found on a tax return form. If you don't have any expenses, then you're done because your adjusted gross income will be the total from your W-2s. If you plan to itemize or you have self-employment income, use Form 1040. If you might itemize a few things such as mortgage interest or certain medical expenses, use Form 1040-A.
Calculate Adjusted Gross Income Using a Form 1040
Examine the tax form and make sure you have included all of your income. If you received a retirement account distribution, dividends, taxable interest, income from real estate or your business showed either a profit or loss, that income has to be counted before you subtract your expenses and adjustments. Once you have accounted for all your wages and income, tally your expenses and adjustments.
Form 1040 allows you to declare the most expenses, so it's the best form to use if you have a lot of expenses you want to subtract from your income. Expenses include educator expenses, business expenses, the health savings account deduction, the deductible part of self-employment tax, retirement plan contributions, self-employment health insurance deductions, early withdrawal penalty for savings accounts, alimony, IRA deductions, student loan interest, tuition and fees and domestic production deduction activities. Once you have a tally of all your expenses, subtract that amount from your gross income. For example, if your W-2s and other income equal $56,000 and you have $15,000 in allowable expenses, your Adjusted Gross Income would be $41,000 ($56,000 - $15,000).
Calculate Adjusted Gross Income Using a Form 1040A
Form 1040A doesn't have as many income allowances (if you have more than is listed on the form, you'll need to switch to the 1040 form). It also doesn't have as many expenses. That said, you'll calculate the AGI in the same manner. Add up your income and wages, then add the total of your expenses, which include educator expenses as well as IRA deductions. Then subtract your expenses from your gross income. If math wasn't your best subject, you can also use a helpful online AGI calculator to help you with the calculations.