W2 Box 12 Codes List & Form W-2 Line 12 Instructions
Confused by letter codes DD, W, D, AA, BB, or K in Box 12 of your Form W-2? Use our complete 2026 IRS decoder matrix to understand what every code means, how elective deferrals affect Box 1 wages, and how to report Box 12 correctly on Form 1040.
Key Takeaways & Executive Summary
Understand Your Employee Benefits & Form W-2 Line 12 Codes
Box 12 codes track health coverage (DD), HSA contributions (W), 401(k) pre-tax elective deferrals (D), designated Roth contributions (AA/BB), uncollected FICA taxes, and golden parachute excise taxes (K). If you also receive 1099 contractor income, generate your official W-9 form securely online.
What is Box 12 on IRS Form W-2?
Box 12 on Form W-2 (Wage and Tax Statement) is used by employers to report various types of compensation and benefits that do not fall neatly into standard payroll categories. This includes pre-tax retirement savings, employer-sponsored healthcare costs, health savings account (HSA) contributions, group-term life insurance, nonqualified deferred compensation, and statutory excise taxes.
Because physical space on a printed W-2 form is limited, the IRS uses one-letter and two-letter codes (Codes A through HH) printed directly next to a dollar amount. You will typically see four sub-lines on Copy B of your W-2 labeled 12a, 12b, 12c, and 12d.
Understanding Form W-2 Lines 12a, 12b, 12c, and 12d
The lowercase letters a, b, c, d next to Box 12 simply indicate the line slot on the form. They are NOT part of the IRS benefit code itself! For example, if line 12a shows DD $8,500, your code is DD. If line 12b shows D $19,500, your code is D. If an employee has more than four Box 12 items, the employer will issue an additional Form W-2.
Search Any IRS W-2 Box 12 Letter Code (A – HH)
| Code | Benefit / Deduction Name | IRS Tax Status | How to Report |
|---|---|---|---|
A | Uncollected Social Security or RRTA Tax on Tips Social security or RRTA tax on tips reported to your employer that could not be collected because you did not have enough wages or other funds from which to withhold. | TAXABLE (ADD TO FORM 1040) | Report this amount as tax owed on Schedule 2 (Form 1040), line 8. |
B | Uncollected Medicare Tax on Tips Medicare tax on tips reported to your employer that could not be collected due to insufficient employee wages or tips. | TAXABLE (ADD TO FORM 1040) | Include this amount on Schedule 2 (Form 1040), line 8. |
C | Taxable Cost of Group-Term Life Insurance Over $50,000 The taxable value of employer-provided group-term life insurance coverage in excess of $50,000. It is already included in Boxes 1, 3, and 5 of your W-2. | TAXABLE (INCLUDED IN BOX 1) | No extra tax form required; this amount is already part of your Box 1 gross wages. |
D | Traditional 401(k) Pre-Tax Elective Deferrals Elective pre-tax salary deferrals to a traditional 401(k) retirement plan (including SIMPLE 401(k)). Lowers your annual Box 1 taxable wages. | PRE-TAX (REDUCES BOX 1) | Informational only. Already subtracted from Box 1. Verifies you did not exceed annual IRS limits ($23,500 in 2025/2026). |
E | Section 403(b) Salary Reduction Contributions Elective pre-tax deferrals under a section 403(b) salary reduction agreement for non-profit, hospital, and public school educators. | PRE-TAX (REDUCES BOX 1) | Already subtracted from Box 1 wages. Tracked against annual statutory retirement limits. |
F | Section 408(k)(6) Salary Reduction SEP Contributions Elective pre-tax deferrals under a salary reduction Simplified Employee Pension (SARSEP) plan. | PRE-TAX (REDUCES BOX 1) | Reduces Box 1 taxable wages; subject to annual IRS contribution caps. |
G | Section 457(b) Deferred Compensation Plan Elective deferrals and employer contributions to a section 457(b) governmental or tax-exempt organization deferred compensation plan. | PRE-TAX (REDUCES BOX 1) | Already excluded from Box 1 federal wages; reported for tracking purposes. |
H | Section 501(c)(18)(D) Tax-Exempt Organization Plan Elective pre-tax deferrals to a section 501(c)(18)(D) tax-exempt organization retirement trust created before June 25, 1959. | PRE-TAX (DEDUCTIBLE ON 1040) | May be deducted on Schedule 1 (Form 1040) as an adjustment to gross income. |
J | Nontaxable Sick Pay Sick pay paid by a third-party insurance carrier that is not subject to income tax because employee premiums paid for the benefit with after-tax money. | NON-TAXABLE (INFO ONLY) | Informational only. Do NOT add to Box 1 income on Form 1040. |
K | 20% Excise Tax on Excess Golden Parachute Payments A 20% federal excise tax on excess golden parachute payments made to corporate officers or key personnel upon a change in company ownership (IRC § 4999). | EXCISE TAX (SCHEDULE 2) | Report on Schedule 2 (Form 1040), line 17k as other additional taxes. |
L | Substantiated Employee Business Expense Reimbursements Nontaxable employee travel, mileage, and meal reimbursements paid under an IRS-compliant accountable plan at standard government rates. | NON-TAXABLE (ACCOUNTABLE PLAN) | Informational only; not taxable and not reported on Form 1040. |
M | Uncollected Social Security/RRTA Tax on Former Employee Life Insurance Uncollected social security or RRTA tax on the taxable cost of group-term life insurance over $50,000 for retired or former employees. | TAXABLE (SCHEDULE 2) | Report on Schedule 2 (Form 1040), line 8. |
N | Uncollected Medicare Tax on Former Employee Life Insurance Uncollected Medicare tax on the taxable cost of group-term life insurance over $50,000 for retired or former employees. | TAXABLE (SCHEDULE 2) | Report on Schedule 2 (Form 1040), line 8. |
P | Excludable Moving Expenses for Armed Forces Members Direct moving expense reimbursements paid to active-duty members of the U.S. Armed Forces for permanent change of station (PCS) orders. | NON-TAXABLE (MILITARY ONLY) | Excluded from gross income; report on IRS Form 3903 if applicable. |
Q | Nontaxable Combat Pay Military combat pay excluded from gross income. Service members can optionally elect to include this in earned income to increase Earned Income Tax Credit (EITC). | NON-TAXABLE (EITC ELIGIBLE) | Enter into tax software to evaluate whether including it boosts your EITC refund. |
R | Employer Contributions to Archer MSA Employer contributions made to an Archer Medical Savings Account (Archer MSA). | REQUIRES FORM 8853 | Must be reported on IRS Form 8853 (Medical Savings Accounts) with your Form 1040 return. |
S | SIMPLE Retirement Plan Salary Reduction Employee salary reduction contributions under an IRS Section 408(p) SIMPLE IRA or SIMPLE 401(k) plan. | PRE-TAX (REDUCES BOX 1) | Already excluded from Box 1 federal wages. Verified against annual SIMPLE caps. |
T | Adoption Benefits Provided by Employer Employer-provided adoption assistance benefits (including amounts paid through a Section 125 cafeteria plan). | REQUIRES FORM 8839 | Must file IRS Form 8839 (Qualified Adoption Expenses) to calculate excludable vs taxable benefits. |
V | Income from Nonstatutory Stock Options (NSO) Income recognized from the exercise of nonstatutory stock options (the spread between market price and strike price). Already included in Box 1, 3, and 5 wages. | TAXABLE (INCLUDED IN BOX 1) | Informational breakdown; no additional tax entry required on Form 1040. |
W | Health Savings Account (HSA) Contributions Combined employer contributions and pre-tax employee payroll deductions to an HSA. Must be reconciled against annual IRS limits. | PRE-TAX (REQUIRES FORM 8889) | CRITICAL: You MUST file IRS Form 8889 with your Form 1040 return to verify HSA compliance. |
Y | Section 409A Nonqualified Deferred Compensation Deferrals Current year deferrals under an IRS Section 409A nonqualified deferred compensation plan. | INFORMATIONAL | Informational only. Not included in Box 1 wages until future distribution occurs. |
Z | Section 409A Nonqualified Plan Failure (20% Penalty) Income under a nonqualified deferred compensation plan that failed IRS Section 409A requirements. Included in Box 1 and triggers an additional 20% federal penalty tax. | TAXABLE + 20% PENALTY | Report penalty tax on Schedule 2 (Form 1040), line 17z. |
AA | Designated Roth 401(k) Contributions Designated after-tax employee elective contributions to a Roth 401(k) retirement plan. Does not reduce Box 1 taxable wages, but future qualifying withdrawals are 100% tax-free. | AFTER-TAX (INCLUDED IN BOX 1) | Already included in Box 1 wages. Informs IRS of your cumulative Roth principal basis. |
BB | Designated Roth 403(b) Contributions Designated after-tax elective contributions to a Roth 403(b) plan for schools, non-profits, and hospitals. | AFTER-TAX (INCLUDED IN BOX 1) | Already included in Box 1 taxable wages. |
DD | Cost of Employer-Sponsored Health Coverage (ACA) Total cost of employer-sponsored group health insurance under the Affordable Care Act (ACA). Includes both employer-paid subsidies and employee payroll deductions. Strictly informational. | INFORMATIONAL (100% NON-TAXABLE) | DO NOT add to taxable income. It is 100% NON-TAXABLE and does NOT alter your refund or tax balance. |
EE | Designated Roth Governmental 457(b) Contributions Designated after-tax contributions to a governmental Roth 457(b) retirement plan. | AFTER-TAX (INCLUDED IN BOX 1) | Already included in Box 1 wages. |
FF | Qualified Small Employer HRA (QSEHRA) Benefits Total permitted health insurance and medical reimbursement benefits under a Qualified Small Employer Health Reimbursement Arrangement. | NON-TAXABLE (QSEHRA) | Informational; used to compute eligibility for ACA health marketplace premium tax credits (Form 8962). |
GG | Section 83(i) Qualified Equity Grants Income Income recognized from qualified stock grants under IRS Section 83(i). | INCLUDED IN BOX 1 | Already included in Box 1 gross taxable wages. |
HH | Section 83(i) Aggregate Deferrals Aggregate deferrals under section 83(i) stock elections as of the close of the calendar year. | INFORMATIONAL | Informational; tracks deferred equity income. |
Elective Deferrals: 401(k), 403(b), 457(b) & Designated Roth Contributions
The most common codes appearing in w2 box 12 represent employee retirement savings:
Code D: Section 401(k) Pre-Tax Elective Deferrals
Reports your voluntary pre-tax elective deferrals to a traditional Section 401(k) plan (up to the annual IRS limit of $23,500 in 2025/2026, plus $7,500 catch-up if age 50+). This money is deducted from your paycheck before calculating federal income tax, so it has already been subtracted from your Box 1 taxable wages.
Code AA & BB: Designated Roth Contributions (401k & 403b)
Code AA reports designated Roth contributions under a Section 401(k) plan, and Code BB reports Roth contributions under a Section 403(b) plan. Roth contributions are made with after-tax dollars. They do not reduce Box 1 income today, but your investment growth and qualified distributions in retirement are 100% tax-free.
Code E & G: Section 403(b) & Section 457(b) Deferrals
Code E represents pre-tax salary reductions for teachers, healthcare workers, and non-profit employees under a 403(b) tax-sheltered annuity. Code G represents elective deferrals under an IRS Section 457(b) deferred compensation plan for state, municipal, and government employees.
Code S: SIMPLE IRA Salary Reduction Contributions
Code S reports employee salary reduction contributions under an IRS Section 408(p) SIMPLE IRA plan for small businesses. Pre-tax contributions are excluded from Box 1 wages.
Health Insurance & HSA Rules (Codes DD, W, FF)
Code DD: Employer-Sponsored Health Coverage Cost (100% Non-Taxable)
Code DD reports the total value of employer-sponsored group health insurance coverage under the Affordable Care Act (ACA). This figure includes both the employer subsidy and employee payroll deductions. Code DD is strictly informational and does NOT increase your taxable income or reduce your tax refund.
Code W: Health Savings Account (HSA) Employer & Pre-Tax Contributions
Code W combines both employer contributions and employee pre-tax payroll deductions to an HSA. When Code W appears on your W-2, you must file IRS Form 8889 with your annual Form 1040 return to verify you did not exceed annual HSA contribution limits ($4,300 single / $8,550 family in 2025/2026).
Code FF: Qualified Small Employer Health Reimbursement (QSEHRA)
Reports permitted benefits under a QSEHRA. This non-taxable reimbursement helps small business employees pay for individual health insurance premiums and medical costs.
What is Box 14 on Form W-2? (Box 14 Codes List Explained)
Box 14 on Form W-2 (labeled "Other") is a designated reporting area where employers provide additional tax information that does not have a dedicated box elsewhere on the form. Unlike Box 12 (which uses strict IRS standard codes A–HH), Box 14 descriptions are created by your employer or payroll provider (ADP, Paychex, Gusto).
Common abbreviations and codes listed in Form W-2 Box 14 include:
| Box 14 Code / Label | Description | Form 1040 Tax Treatment |
|---|---|---|
| CASDI / SDI / TDI | State Disability Insurance | Mandatory state deduction (CA, NY, NJ, HI, RI). May be deductible on Schedule A. |
| NY PFL / NJ FLI | Paid Family Leave Insurance | State mandatory family leave program deduction. |
| UNION / UNION DUES | Union Dues Deductions | Informational (not federally deductible for W-2 workers under TCJA). |
| SEC 127 / EDU ASSIST | Employer Educational Assistance | Tax-free tuition/loan reimbursement up to $5,250 annually. |
| AUTO / LEASE VAL | Company Car Personal Use Value | Taxable fringe benefit already included in Box 1 wages. |
| 114B / MAND RET | Mandatory State Retirement | State government employee mandatory pension contributions. |
What is Box D on Form W-2? (Control Number Decoded)
Box D on Form W-2 is labeled "Control number". It is an internal alphanumeric code assigned by your employer's payroll processing company (such as ADP, Paychex, Quickbooks, or Workday) to uniquely track your specific W-2 document within their automated systems.
Key Facts About Box D (Control Number):
- Where is Box D? It is located on the middle-left side of your printed Form W-2, directly below your employer's name and address (Box c).
- Is Box D Required for E-Filing? No! The IRS does NOT require a Control Number to accept your electronic tax return. If Box D is blank on your form, simply leave the field empty in TurboTax, H&R Block, or TaxAct.
- What if my Box D is blank? Leaving Box D blank will never delay your IRS tax refund or cause your return to be rejected.
Uncollected Social Security & Section 83 Deferrals (Codes A, B, M, N, Y, Z)
Certain Box 12 codes indicate specialized statutory tax obligations or executive deferred compensation:
- Codes A & B (Uncollected Social Security & Medicare on Tips): When an employee receives cash tips but does not earn enough regular wages for the employer to withhold full FICA taxes, the unpaid tax is reported in Box 12 with Code A (Social Security) and Code B (Medicare). This must be reported as extra tax on Form 1040 Schedule 2.
- Codes M & N (Uncollected FICA on Group-Term Life Insurance): Applies to former employees or retirees who received taxable group-term life insurance over $50,000 where FICA taxes were not withheld.
- Code Y & Z (Section 409A & Section 83 Deferrals): Code Y reports deferrals under section 83 and Section 409A nonqualified deferred compensation plans. Code Z represents nonqualified deferred compensation that fails IRS Section 409A requirements, triggering a mandatory 20% penalty tax plus interest.
- Code K (Golden Parachute Payments): Reports a 20% federal excise tax on excess golden parachute payments under IRC § 4999, reported directly on Form 1040 Schedule 2.
Step-by-Step: How to Report Form W-2 Line 12 Codes on Form 1040
When preparing your federal income tax return, follow this structured process for handling Box 12 codes:
- Do NOT adjust Box 1 manually: Your employer has already subtracted pre-tax deferrals (Codes D, E, G, S) and already added taxable benefits (Code C, V) into Box 1. Never add or subtract these figures manually on Form 1040 Line 1a.
- Match the uppercase letter code exactly: When entering your W-2 in tax software, select the exact letter code (e.g., Code DD or Code W) from the drop-down menu corresponding to the sub-line (12a–12d).
- Attach mandatory supporting IRS forms:
- If Code W is present → Complete and attach IRS Form 8889 (Health Savings Accounts).
- If Codes A, B, M, N, or K are present → Report additional tax on Schedule 2 (Form 1040).
- If Code V (exercise of nonstatutory stock options) is present → Track capital gains on Schedule D & Form 8949 upon sale.
- Verify Retirement Saver's Credit: Pre-tax contributions in Box 12 (Codes D, E, G, S) and Roth contributions (Codes AA, BB) may qualify you for the Retirement Savings Contributions Credit (Saver's Credit) on Form 8880, saving you up to $1,000 ($2,000 married).
Moving from W-2 Employee to 1099 Freelancer?
If you transition from a traditional W-2 job to 1099 freelance or independent contracting work, you will no longer receive a Form W-2 with Box 12 codes at year-end.
Instead of employer-provided benefits, you become responsible for purchasing your own health insurance and retirement plans. The good news? You can write off 100% of self-employed health insurance premiums and 50% of self-employment tax directly on Schedule C!
Before receiving payments from new clients, you will be required to provide a signed Form W-9. You can generate an official IRS-ready W-9 PDF in under 60 seconds with our free 2026 Form W-9 Generator or calculate your estimated take-home pay with our Paystub Maker.
Frequently Asked Questions
Statutory References & Legal Citations
This publication is audited against official federal statutes, Treasury regulations, and published IRS bulletins. Verified primary source references are provided below for independent legal and accounting cross-examination.
Explore Free Compliance Calculators & Generators
Client-side encrypted, free IRS tax document generators and 2026 payroll tax calculators.
Fill, sign, and download official IRS Form W-9 (Rev. March 2024) PDFs with zero server data storage.
Estimate net take-home pay after federal brackets, state tax, and FICA payroll deductions.
Track federal & 50-state tax refunds, transcript code 846 direct deposit dates, and PATH Act holds.
Auto-fill tax treaty benefits for 25+ countries to reduce or eliminate the 30% foreign withholding.
Generate professional pay stubs with itemized FICA, overtime, pre-tax benefits, and PDF export.
Calculate 1099 self-employment tax, 50% SE deduction, and quarterly estimated voucher payments.