Box 12: Deferred Compensation and Other Compensation. There are several types of compensation and benefits that can be reported in Box 12. Box 12 will report a single letter or double letter code followed by a dollar amount. Here are the codes for Box 12.
Box 13: Check the Box. There are three check boxes in Box 13. Boxes will be checked off if any of these situations apply to you as an employee.
Statutory employee means that you report the wages from this W-2 (and any other W-2 forms marked "statutory employee") on Form 1040 Schedule C. Your wages are not subject to income tax withholding (there will be a zero or blank amount in Box 2), but are subject to Social Security and Medicare taxes (so Boxes 3 through 6 will be filled out).
Retirement plan means that you participated in your employer's retirement plan during the year. This might be a 401(k) plan, profit-sharing plan, or pension plan. As a participate in a retirement plan, your ability to deduct contributions to a tax-deductible traditional IRA may be limited.
Third-party sick pay means that you received sick pay under your employer's third-party insurance policy. (Instead of receiving sick pay directly from your employer as part of your regular paycheck.) Sick pay is not included in your taxable wages.
Box 14: Other Tax Information. Your employer may report additional tax information in Box 14. If any amounts are reported, they will have a brief description of what the amounts are for. For example, union dues, employer-paid tuition assistance, or after-tax contributions to a retirement plan may be reported here. Some employers report certain state and local taxes in Box 14, such as State Disability Insurance (SDI) premiums.
Box 15: State and State Employer's Identification. Box 15 reports your employer's state and state tax identification number. If you worked for the same employer in multiple states, there may be multiple lines of information.
Box 16: State wages. Box 16 reports the total amount of taxable wages earned in that state. If you worked for the same employer in multiple state, there may be multiple lines of information.
Box 17: State income tax withheld. Box 17 reports the total amount of state income taxes withheld from your paychecks for the wages reported in Box 16.
Box 18: Local wages. Box 18 reports the total amount of wages subject to local, city, or other state income taxes.
Box 19: Local income tax withheld. Box 19 reports the total amount of taxes withheld from your paychecks for local, city, or other state income taxes.
Box 20: Locality name. Box 20 provides a brief description of the local, city, or other state tax being paid. The description may identify a particular city, or may identify a state tax such as State Disability Insurance (SDI) payments.
More about Form W-2: