Paycheck guides
Three different wage figures, none of them your salary. Here is what each box on the form actually reports, and why they disagree with each other on purpose.
The W-2 is a summary of what your employer paid you and what they sent to the government on your behalf. Most of the confusion it causes comes from one fact: it reports your wages three separate times, and the three numbers rarely match. That is not an error. Each figure is measured against a different tax, and each tax has different rules about what counts.
This is your taxable pay for federal income tax. It is your gross pay minus anything you contributed that is exempt from income tax: traditional 401(k) or 403(b) deferrals, health insurance premiums paid through a cafeteria plan, HSA contributions made by payroll deduction, FSA contributions, and commuter benefits.
If you earned $70,000 and put $7,000 into a traditional 401(k) plus $3,000 in health premiums, Box 1 reads $60,000. This is the number most people find alarming and then relieving — it is lower than their salary because they saved money, not because anything went wrong.
The base for the 6.2% Social Security tax. It differs from Box 1 in two directions at once:
Health premiums and FSA contributions are exempt from FICA, so those still reduce Box 3.
The base for the 1.45% Medicare tax. Same rules as Box 3, with one critical difference: there is no cap. On a $300,000 salary, Box 3 shows $184,500 and Box 5 shows the full amount less any pre-tax health and FSA money. Box 5 is usually the largest of the three.
A quick sanity check: Box 4 should equal 6.2% of Box 3, and Box 6 should equal 1.45% of Box 5 — plus 0.9% on anything in Box 5 above $200,000. If Box 4 exceeds $11,439.00 for 2026, something is wrong, because that is 6.2% of the wage base.
That last point trips up married couples. The Additional Medicare Tax threshold on your return is $250,000 for joint filers, but each employer withholds based on a $200,000 threshold because they cannot see your spouse’s income. Two spouses each earning $150,000 will have nothing withheld yet owe the tax on $50,000 of combined wages. Form 8959 reconciles it.
Box 12 is where the gap between your salary and Box 1 gets itemised. The codes you are most likely to see:
| Code | What it reports |
|---|---|
| D | Traditional 401(k) elective deferrals |
| AA | Roth 401(k) contributions — already taxed, so they do not reduce Box 1 |
| E | 403(b) deferrals |
| W | HSA contributions, both yours and your employer’s |
| DD | Cost of employer-sponsored health coverage — informational only, not taxable |
| C | Taxable cost of group-term life insurance over $50,000 |
Code DD alarms people every year. It is the total cost of your health plan including the employer’s share, reported for transparency under the Affordable Care Act. It is not income and it is not taxed.
Box 16 is your state taxable wages and Box 17 is what was withheld. Box 16 will not always match Box 1, because states differ on what they exempt — some do not follow the federal treatment of HSA contributions, for instance. Boxes 18 to 20 cover local income taxes in the cities and counties that levy them.
If you worked in more than one state, you should see multiple rows here, and you will likely need to file in each.
If something does not reconcile, the fix is a corrected W-2 (Form W-2c) from your employer, not an adjustment on your return.
Sources: IRS General Instructions for Forms W-2 and W-3; IRS Publication 15 (Circular E) for 2026; Social Security Administration contribution and benefit base for 2026; IRS Topic No. 560, Additional Medicare Tax.
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