Box 1: Wages, salaries, tips and other compensation you receive from your employer for your services. This amount should be reported on the "Wages, salaries, tips, etc. " line of your Form 1040 or 1040A, or on the corresponding line if you are filing Form 1040EZ.
Box 2: Federal income tax withheld. This should be reported on the federal income tax withholding line of your tax return. Even if you are not required to file a return, but federal income tax has been withheld, you should file a return to claim the Earned Income Credit and to obtain a refund of federal income tax withheld that is more than your tax liability. If, once you have completed your income tax return, you find that the amount withheld was either excessive or insufficient, you may need to ask your employer to revise your W-4 tax withholding form.
Box 3: Social security wages - the amount of your compensation subject to social security tax. Employees pay a certain percentage for social security tax (Old Age, Survivors and Disability Insurance, or "OASDI") on their earnings up to a maximum amount per year. This ceiling amount is subject to change and is published by the IRS and other government entities each year. If your total compensation is less than the maximum amount on which social security tax applies, this will be the same amount as in box 1. If you earned more than the maximum amount subject to Social Security tax, this box will show the maximum amount.
Note: If you had more than one employer during the year, you should check the combined totals of your W-2’s to see if you paid more than the required amount of social security tax; that is, whether your total income for the year went over the maximum amount subject to social security tax. If so, you can claim a credit for the excess amount withheld on the line entitled " Excess social security and tier 1 RRTA tax withheld" in the "Payments" section of Form 1040. If this is the case, you cannot use Form 1040EZ or 1040A.
Box 4: This is the Social Security (OASDI) tax withheld, up to the maximum amount each year, and does not need to be reported on your income tax return.