W-2 Form

Every January, every U.S. employer runs the same set of tasks: reconcile the year's payroll totals, run validation against SSA's Accuwage, generate W-2s, and get them to employees and the government by January 31. Done right, the process is boring. Done wrong, it produces corrected W-2s (Form W-2c), IRS notices, and angry employees trying to file their own taxes with paperwork that doesn't match their own records. The W-2 isn't just a form. It's the year-end proof that payroll ran correctly, and the most visible communication an employer sends about an employee's total compensation.

What Each W-2 Box Actually Reports

Box 1 is federal taxable wages: gross pay minus pre-tax deductions like 401(k), Section 125 cafeteria plan premiums, and qualified transit benefits. Box 2 is the federal income tax withheld during the year. Boxes 3 and 4 report Social Security wages and Social Security tax, with wages capped at the annual wage base ($184,500 for 2026). Boxes 5 and 6 cover Medicare wages and Medicare tax, which have no cap. Boxes 15 through 20 handle state and local tax.

Box 12 uses single-letter codes to identify specific items: Code D for traditional 401(k) contributions, Code AA for Roth 401(k), Code DD for employer-paid health coverage, Code W for HSA contributions, Code C for group-term life insurance over $50,000, and many more. Box 14 is a catch-all the employer can use for items that don't fit elsewhere (state disability insurance, union dues, and so on).

Who Gets a W-2 and When

Every employee who had federal, state, Social Security, or Medicare tax withheld during the year, or who earned at least $600, receives a W-2. Independent contractors receive Form 1099-NEC instead, not a W-2, because no employment relationship or withholding applies. Employees terminated mid-year still receive a W-2 covering their time on payroll, due January 31 of the following year.

The employer files Copy A with the SSA (electronic filing is required for most employers), provides Copy B, C, and 2 to the employee, and keeps Copy D for their records. Most payroll systems generate all copies automatically.

What If the W-2 Is Wrong?

Wrong W-2s get corrected with Form W-2c. Common errors include incorrect Social Security numbers, wrong employer identification numbers, mismatched wages, or missing Box 12 codes. W-2c should be filed as soon as the error is discovered. Employees who've already filed taxes based on the wrong W-2 may need to file an amended return, which is a visible employee-experience issue.

2026 W-2 Changes to Watch

Two 2026 changes affect W-2 preparation. The Social Security wage base rose to $184,500, which means Box 3 wages cap at that number and Box 4 caps at $11,439 of employee Social Security tax. SECURE 2.0's Roth catch-up requirement for high earners (Social Security wages above $150,000 in the prior year) fully took effect, which means catch-up contributions for those employees must be Roth (reported in Box 12 with Code AA) rather than traditional.

Payroll systems had to be updated to route catch-up dollars correctly starting January 2026. Employers who haven't fully validated the routing will see W-2 discrepancies surface at year-end.

Running a W-2 Season That Doesn't Generate Corrections

Four practices prevent most errors. Run the SSA's Accuwage tool on the W-2 file before submission to catch formatting and validation errors. Reconcile quarterly 941s to the annual W-3 totals before January 31. Validate Box 12 codes against the year's fringe benefits data (imputed income, HSA contributions, 401(k) split between traditional and Roth). Give employees a preview of their W-2 earnings summary in mid-December so they can flag issues before the form is final.

Pair W-2 preparation with year-end payroll reconciliation, FICA and Medicare tax accuracy checks, and withholding review. Reference the IRS General Instructions for Forms W-2 and W-3, the SSA Business Services Online portal, and the IRS About Form W-2 page each year for threshold and procedure updates.