W-2 Box Guide — Every Box Explained
Your W-2 (Wage and Tax Statement) has 20 boxes plus Box 12's alphabet-soup codes and most employees only look at Boxes 1 and 2. This guide explains the 18 most commonly questioned W-2 boxes, what each one feeds on Form 1040, and what to double-check against your final pay stub before you file.
All W-2 boxes at a glance
| Box | What it reports | Where it goes on your return |
|---|---|---|
| Box 1 | Wages, tips, other compensation | Form 1040, Line 1a |
| Box 2 | Federal income tax withheld | Form 1040, Line 25a |
| Box 3 | Social security wages | Not reported on 1040 directly. |
| Box 4 | Social security tax withheld | Not reported on 1040 directly (except for excess from multiple employers — Schedule 3, Line 11). |
| Box 5 | Medicare wages and tips | Not reported on 1040 directly. |
| Box 6 | Medicare tax withheld | Feeds Form 8959 (Additional Medicare Tax); not on 1040 directly. |
| Box 10 | Dependent care benefits | Form 2441, Part III — Dependent Care Benefits. |
| Box 11 | Nonqualified plans | Included in Box 1 (Line 1a on 1040) — Box 11 is informational for Social Security earnings. |
| Box 12 | Codes (401(k), HSA, health coverage, ISO, and more) | Varies by code. Some feed Form 8889 (HSA), others Form 3903 (moving), etc. Many are informational only. |
| Box 12 Code D | Elective deferrals to a 401(k) plan | Already reflected in Box 1 (reduces it). Feeds Form 8880 (Saver's Credit). |
| Box 12 Code DD | Cost of employer-sponsored health coverage | None — informational only. |
| Box 12 Code E | Elective deferrals to a 403(b) plan | Already reflected in Box 1. Feeds Form 8880 (Saver's Credit). |
| Box 12 Code W | Employer and employee HSA contributions | Must be reconciled on Form 8889, Part I. |
| Box 12 Code AA | Roth 401(k) contributions | Already in Box 1. Feeds Form 8880 (Saver's Credit). |
| Box 12 Code BB | Roth 403(b) contributions | Already in Box 1. Feeds Form 8880 (Saver's Credit). |
| Box 13 | Statutory employee · Retirement plan · Third-party sick pay | Varies — statutory employee amounts go to Schedule C; retirement plan box affects IRA deductibility. |
| Box 14 | Other (state disability, union dues, RRTA, NYC SDI, and more) | Varies by item — some are deductible, some informational, some already in Box 1. |
| Box 15 | State · Employer's state ID number | Reported on the corresponding state return — not on Form 1040. |
Wages & federal tax withheld
The two boxes every W-2 recipient looks at first — taxable wages and federal income tax held back.
Box 1 — Wages, tips, other compensation
Your taxable federal wages for the year — gross pay minus pre-tax deductions like traditional 401(k), Section 125 cafeteria plan contributions, and pre-tax HSA.
Box 2 — Federal income tax withheld
Total federal income tax your employer withheld from your paychecks during the year, based on your Form W-4 elections.
Social Security (FICA OASDI)
Wages subject to Social Security and the 6.2% tax — capped at the annual wage base.
Box 3 — Social security wages
Your wages subject to Social Security tax, capped at the annual wage base. Differs from Box 1 because traditional 401(k) deferrals are not excluded.
Box 4 — Social security tax withheld
The Social Security tax your employer withheld — exactly 6.2% of Box 3 (plus Box 7 tips), capped at 6.2% of the annual wage base.
Medicare (FICA HI)
Medicare wages and the 1.45% tax, plus 0.9% Additional Medicare Tax above $200,000.
Box 5 — Medicare wages and tips
Your wages subject to Medicare tax. Unlike Social Security, there is no wage base cap — Box 5 can exceed Box 3 on high salaries.
Box 6 — Medicare tax withheld
1.45% of Box 5, plus 0.9% Additional Medicare Tax on the portion of Box 5 above $200,000 at any single employer.
Dependent care & nonqualified plans
Dependent care FSA benefits and 409A deferred-comp distributions.
Box 10 — Dependent care benefits
Total dependent care benefits your employer paid (including through a Section 129 dependent care FSA). Up to $5,000 MFJ can be excluded from Box 1.
Box 11 — Nonqualified plans
Distributions from a nonqualified deferred compensation plan (Section 409A), or certain amounts included in Box 1 from a prior year's elective deferral.
Box 12 — coded amounts
The catch-all coded box — 401(k), 403(b), HSA, Roth, and the big informational DD (employer health coverage cost).
Box 12 — Codes (401(k), HSA, health coverage, ISO, and more)
Up to four labeled amounts (12a–12d) using IRS codes. Common codes: D (401(k) elective deferral), DD (employer health coverage cost), W (employer + employee HSA contributions), AA (Roth 401(k)).
Box 12 Code D — Elective deferrals to a 401(k) plan
Your traditional (pre-tax) 401(k) elective deferrals. Reduces Box 1 dollar-for-dollar, up to the annual §402(g) elective deferral limit (higher with age-50 catch-up and SECURE 2.0 ages-60–63 super-catch-up).
Box 12 Code DD — Cost of employer-sponsored health coverage
The total cost (employer + employee share) of your employer-sponsored group health coverage. Informational only — does not affect your tax.
Box 12 Code E — Elective deferrals to a 403(b) plan
Your traditional (pre-tax) 403(b) elective deferrals. Reduces Box 1 up to the annual §402(g) limit, with a special 15-year catch-up for long-tenured employees of certain nonprofits.
Box 12 Code W — Employer and employee HSA contributions
Total Health Savings Account contributions — both employer and employee (via pre-tax payroll). Capped at the §223 annual HSA limit for your HDHP coverage tier, plus the $1,000 age-55+ catch-up under §223(b)(3)(B)(ii).
Box 12 Code AA — Roth 401(k) contributions
Your designated Roth 401(k) contributions. Already included in Box 1 (taxed now), but qualified distributions in retirement are tax-free.
Box 12 Code BB — Roth 403(b) contributions
Your designated Roth 403(b) contributions. Already included in Box 1 (taxed now); qualified distributions are tax-free.
Box 13 checkboxes & Box 14 other
Statutory employee, retirement plan coverage, third-party sick pay, plus state disability insurance and union dues.
Box 13 — Statutory employee · Retirement plan · Third-party sick pay
Three checkboxes (not dollar amounts): Statutory employee, Retirement plan coverage, Third-party sick pay. Each has separate tax-return implications.
Box 14 — Other (state disability, union dues, RRTA, NYC SDI, and more)
Free-form 'Other' box used by employers for items not covered elsewhere — state disability insurance, union dues, uniform allowances, educational assistance above $5,250, etc.
State income tax (Boxes 15–20)
State identification and withholding — multi-state workers and remote employees should read this one.
Box 12 codes — complete list
All 30 IRS Box 12 codes, per the IRS General Instructions for Forms W-2 and W-3. A W-2 shows up to four per employer (12a–12d).
| Code | Meaning | Tax treatment |
|---|---|---|
| A | Uncollected Social Security or RRTA tax on tips | Not withheld — you owe it (Schedule 2) |
| B | Uncollected Medicare tax on tips | Not withheld — you owe it (Schedule 2) |
| C | Taxable cost of group-term life insurance over $50,000 | Included in Box 1 — already taxed |
| D | Elective deferrals to a 401(k) plan | Pre-tax; reduces Box 1 |
| E | Elective deferrals to a 403(b) plan | Pre-tax; reduces Box 1 |
| F | Elective deferrals to a 408(k)(6) salary-reduction SEP | Pre-tax; reduces Box 1 |
| G | Elective deferrals to a 457(b) plan | Pre-tax; reduces Box 1 |
| H | Elective deferrals to a 501(c)(18)(D) plan | Pre-tax; reduces Box 1 |
| J | Nontaxable sick pay | Not taxable — informational |
| K | 20% excise tax on excess golden parachute payments | Additional tax already withheld |
| L | Substantiated employee business expense reimbursements | Not taxable — informational |
| M | Uncollected Social Security or RRTA tax on group-term life over $50,000 (former employees) | Not withheld — you owe it (Schedule 2) |
| N | Uncollected Medicare tax on group-term life over $50,000 (former employees) | Not withheld — you owe it (Schedule 2) |
| P | Excludable moving expense reimbursements (U.S. Armed Forces only) | Not taxable — informational |
| Q | Nontaxable combat pay | Not taxable — may still count as earned income for EITC |
| R | Employer contributions to an Archer MSA | Not taxable — informational; may need Form 8853 |
| S | Employee salary-reduction contributions to a 408(p) SIMPLE | Pre-tax; reduces Box 1 |
| T | Employer-provided adoption benefits | Not taxable up to the exclusion limit — Form 8839 |
| V | Income from exercise of nonstatutory stock options | Included in Boxes 1, 3, 5 — already taxed |
| W | Employer and employee HSA contributions via a cafeteria plan | Pre-tax; reduces Box 1 — reconcile on Form 8889 |
| Y | Deferrals under a Section 409A nonqualified deferred compensation plan | Not yet taxable — informational |
| Z | Income under a failed Section 409A plan | Taxable now, plus a 20% additional tax |
| AA | Designated Roth contributions to a 401(k) plan | After-tax; already included in Box 1 |
| BB | Designated Roth contributions to a 403(b) plan | After-tax; already included in Box 1 |
| DD | Cost of employer-sponsored health coverage | Not taxable — informational only |
| EE | Designated Roth contributions to a governmental 457(b) plan | After-tax; already included in Box 1 |
| FF | Permitted benefits under a Qualified Small Employer HRA (QSEHRA) | Not taxable — informational |
| GG | Income from qualified equity grants under Section 83(i) | Deferred taxation — informational until income is recognized |
| HH | Aggregate deferrals under Section 83(i) elections | Deferred taxation — informational |
| II | Medicaid waiver payments excluded from gross income under Notice 2014-7 | Not taxable — excluded from Box 1 |
Reconciling your W-2 at tax time? Use the paycheck calculator to verify expected federal, Social Security, and Medicare withholdings on your salary, then the federal income tax calculator to estimate your refund or balance owing before April 15.
Frequently asked questions
What do the W-2 boxes mean?
Each numbered box on your W-2 reports a specific piece of pay or withholding — wages, federal/state tax withheld, Social Security and Medicare wages and tax, plus coded benefit amounts in Box 12. See the quick-reference table above for what each box reports and where it goes on your return.
Why is Box 1 lower than Box 3 and Box 5?
Pre-tax deductions like traditional 401(k)/403(b) elective deferrals and Section 125 cafeteria-plan contributions reduce Box 1 (taxable federal wages) but are not exempt from Social Security or Medicare tax the same way, so Box 3 and Box 5 stay higher.
What are the W-2 Box 12 codes?
Box 12 uses two-letter IRS codes to identify specific types of pay or benefits — up to four per W-2. The most common are D (401(k) deferral), DD (employer health coverage cost, informational only), W (HSA contributions), and AA (Roth 401(k)). See the complete code list above.
What should I check before filing?
Match your W-2 boxes against your final (year-end) pay stub's YTD totals. If you had multiple employers, each issues its own W-2 — enter each separately; Box 1 amounts from all employers sum on Form 1040, Line 1a.
Sources
W-2 box definitions per IRS General Instructions for Forms W-2 and W-3 and IRC §6051. Box structure is statutory and stable year to year; year-indexed limits shown on each box's page update from central config.