# What will my W2 wages be?

Works out the wage boxes of your Form W-2 (box 1 taxable wages, boxes 3 and 5 Social Security and Medicare wages, boxes 4 and 6 tax withheld) from gross pay and pre-tax deductions.

- Page: https://www.acalculator.org/finance/w2-calculator
- JSON spec: https://www.acalculator.org/finance/w2-calculator.json
- Version: bcd9bfea147b

## Default answer

Example with the default inputs (Gross pay for the year $75,000.00, Pre-tax retirement deferrals $6,000.00, Section 125 deductions $3,000.00, Pre-tax commuter benefits $0.00, W-2 year 2,026): On $75,000.00 of gross pay, box 1 of your W-2 shows $66,000.00, and boxes 3 and 5 show $72,000.00 and $72,000.00.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| gross | Gross pay for the year | All pay before any deduction: salary, hourly pay, overtime, bonuses, commissions, taxable tips. |
| k401 | Pre-tax retirement deferrals | Traditional (not Roth) 401(k), 403(b), 457(b), or SIMPLE IRA contributions taken from your pay (box 12 codes D, E, G, S). |
| sec125 | Section 125 deductions | Pre-tax health, dental, and vision premiums, health or dependent care FSA, and HSA contributions through payroll. |
| commute | Pre-tax commuter benefits | Transit pass and parking taken pre-tax for the year: at most $340 a month each in 2026, $8,160 a year. |
| year | W-2 year | The year of the pay. A year with no published wage base uses the latest year this site has. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| box1 | Box 1: wages, tips, other compensation | Gross pay less retirement deferrals, section 125 deductions, and commuter benefits. |
| box3 | Box 3: Social Security wages | Gross pay less section 125 and commuter deductions, up to the wage base. |
| box4 | Box 4: Social Security tax withheld | 6.2% of box 3. |
| box5 | Box 5: Medicare wages and tips | Gross pay less section 125 and commuter deductions, with no limit. |
| box6 | Box 6: Medicare tax withheld | 1.45% of box 5, plus 0.9% of box 5 over $200,000. |
| box12 | Box 12: retirement deferrals | The pre-tax deferrals, shown with their code (D for a 401(k)). |
| excluded | Left out of every wage box | Section 125 deductions plus commuter benefits. |
| gap | Box 5 minus box 1 | Why box 1 is lower than your Medicare wages: the retirement deferrals. |
| notice | Note | A note when another year’s wage base was used. |

## Method

Box 5 = gross − section 125 − commuter benefits. Box 1 = box 5 − pre-tax retirement deferrals. Box 3 = the lesser of box 5 and the Social Security wage base ($184,500 in 2026). Box 4 = 6.2% × box 3. Box 6 = 1.45% × box 5 + 0.9% × (box 5 − $200,000, if above 0). Box 12 = the deferrals.

## Assumptions

- One employer for the whole year. With two jobs, each W-2 has its own wage base and $200,000 withholding threshold.
- Roth 401(k) contributions, after-tax deductions, and wage garnishments do not change any wage box.
- Group-term life insurance over $50,000, taxable fringe benefits, dependent care benefits over $5,000, and commuter benefits over the monthly limit add to the boxes and are not included.
- Box 2 (federal income tax withheld) depends on your Form W-4 and pay periods: use the federal withholding calculator.

## Worked examples

1. gross = $75,000.00, k401 = $6,000.00, sec125 = $3,000.00, commute = $1,200.00 gives box1 = $64,800.00, box3 = $70,800.00, box4 = $4,389.60, box5 = $70,800.00, box6 = $1,026.60, box12 = $6,000.00. Source: IRS 401(k) plan overview (deferrals stay in Social Security and Medicare wages); IRS cafeteria plan FAQ and Pub 15-B Table 2-1 (section 125 and commuter benefits excluded from all three).
2. gross = $250,000.00, k401 = $24,500.00, sec125 = $0.00, commute = $0.00 gives box1 = $225,500.00, box3 = $184,500.00, box4 = $11,439.00, box5 = $250,000.00, box6 = $4,075.00. Source: Pub 15 (2026): Social Security wage base $184,500; Additional Medicare Tax withheld at 0.9% over $200,000.
3. gross = $40,000.00, k401 = $0.00, sec125 = $0.00, commute = $0.00 gives box1 = $40,000.00, box3 = $40,000.00, box4 = $2,480.00, box6 = $580.00.

## FAQ

### Why is box 1 of my W-2 lower than my salary?

Box 1 leaves out pre-tax deductions: traditional 401(k), 403(b), and 457(b) deferrals, section 125 cafeteria plan deductions (health premiums, FSA, HSA through payroll), and pre-tax commuter benefits. Those amounts are not taxed as income this year.

### Why are boxes 3 and 5 higher than box 1?

Retirement deferrals are excluded from income tax but still count as wages for Social Security and Medicare (IRS, 401(k) plan overview). So box 3 and box 5 include them; box 1 does not. Section 125 and commuter deductions are left out of all three.

### What is the most box 3 can show in 2026?

$184,500, the 2026 Social Security wage base (IRS Publication 15). Box 4 is then at most 6.2% of it, $11,439. Box 5 has no limit.

### Why is box 6 more than 1.45% of box 5?

Your employer must withhold an extra 0.9% Additional Medicare Tax on wages over $200,000 in the year, whatever your filing status. Box 6 includes it.

### Can I use my last pay stub to estimate my W-2?

Yes. Use the year-to-date gross pay and year-to-date pre-tax deductions from your last pay stub of the year. Box 1 should match year-to-date taxable wages on the stub, if your payroll shows it.

### Do Roth 401(k) contributions lower box 1?

No. Roth contributions are taken after tax, so they stay in boxes 1, 3, and 5. Your employer shows them in box 12 with code AA.

## Sources

- IRS, General Instructions for Forms W-2 and W-3 (2026). https://www.irs.gov/instructions/iw2w3 (retrieved 2026-10-05)
- IRS, 401(k) resource guide, plan participants: 401(k) plan overview (deferrals are wages for Social Security, Medicare, and FUTA). https://www.irs.gov/retirement-plans/plan-participant-employee/401k-resource-guide-plan-participants-401k-plan-overview (retrieved 2026-10-05)
- IRS, FAQs for government entities regarding cafeteria plans (salary reductions not wages for income tax, FICA, or FUTA). https://www.irs.gov/government-entities/federal-state-local-governments/faqs-for-government-entities-regarding-cafeteria-plans (retrieved 2026-10-05)
- IRS, Publication 15-B (2026), Employer’s Tax Guide to Fringe Benefits: Table 2-1 and the $340 monthly transportation limits. https://www.irs.gov/publications/p15b (retrieved 2026-10-05)
- IRS, Publication 15 (2026), Employer’s Tax Guide: Social Security wage base $184,500, rates, and Additional Medicare Tax withholding. https://www.irs.gov/publications/p15 (retrieved 2026-10-05)