How to Find W-2 Taxable Income: Box 1, Codes, and Pre-Tax Deductions

Your federal taxable income from a W-2 is in Box 1, labeled “Wages, tips, other compensation.” That is the figure you carry to line 1a of Form 1040.¹ If you want to know how to find W-2 taxable income and understand why it doesn’t match the other wage boxes on the same form, the short answer is that Box 1 already has your pre-tax deductions subtracted out, while Boxes 3 and 5 (Social Security and Medicare wages) generally do not.

What Box 1 Actually Contains

Box 1 is your total pay for the year minus any pre-tax deductions your employer took out before calculating federal income tax. Traditional 401(k) contributions, health insurance premiums paid through a cafeteria plan, and similar pre-tax benefits all shrink this number before it prints on the form.

Box 1 also picks up items beyond regular salary. Taxable fringe benefits are added in, including the cost of employer-provided group life insurance coverage above $50,000.² Bonuses, commissions, and tips you reported to your employer belong here too. Personal use of a company car gets valued and included.

One detail catches people off guard: Roth 401(k) contributions are included in Box 1, even though traditional 401(k) contributions are not. Both types appear in Box 12, but because Roth contributions are made with after-tax dollars, they stay in your federal taxable wages.³ If Box 1 looks higher than you expected and you contribute to a Roth 401(k), that’s usually the reason.

Why Box 1 Doesn’t Match Box 3 or Box 5

Almost every W-2 shows three different wage numbers in Boxes 1, 3, and 5. The reason is that federal income tax, Social Security tax, and Medicare tax follow different rules about which deductions apply.

Most pre-tax payroll deductions reduce Box 1 but do not reduce Boxes 3 and 5. Traditional 401(k) and 403(b) contributions are the most common example. If you deferred $10,000 into a traditional 401(k), your employer subtracted that $10,000 from Box 1 because the federal government defers income tax on those contributions until you withdraw the money in retirement. Social Security and Medicare taxes still applied to that $10,000, so Boxes 3 and 5 stay higher.³

The same pattern applies to health insurance premiums paid through a Section 125 cafeteria plan, flexible spending account contributions, and health savings account contributions. All of these reduce Box 1 but generally still count as Social Security and Medicare wages. The typical result is that Boxes 3 and 5 come out higher than Box 1.

One thing pulls in the other direction: the Social Security wage cap. For 2026, only the first $184,500 of your earnings is subject to Social Security tax.⁴ If a single employer paid you more than that, Box 3 will show $184,500 rather than your full pay, and it can end up lower than Box 1. Medicare has no cap, so Box 5 keeps climbing.⁵

Pre-Tax Deductions That Lower Box 1

To reconcile your last pay stub with your W-2, work through the deductions that were excluded from federal taxable wages. The most common ones:

Traditional 401(k) and 403(b) contributions. For 2026, employees can defer up to $24,500 pre-tax, with an additional $8,000 catch-up at age 50 or older ($11,250 at ages 60 through 63). These appear in Box 12 with Code D (401(k)) or Code E (403(b)) and are excluded from Box 1.⁶⁷
Health insurance premiums. Medical, dental, and vision premiums paid through a cafeteria plan are excluded from Box 1.
Health savings account contributions. For 2026, you can contribute up to $4,400 with self-only coverage or $8,750 with family coverage on a pre-tax basis through payroll. These appear in Box 12 with Code W.⁸
Dependent care FSA contributions. Up to $7,500 can be excluded from taxable income in 2026 ($3,750 if married filing separately), reported in Box 10.⁹
Medical FSA contributions. Money set aside in a healthcare flexible spending account through your employer’s cafeteria plan also reduces Box 1.

A worked example: gross pay of $80,000, with $5,000 into a traditional 401(k) and $3,000 in cafeteria-plan health premiums, produces a Box 1 of roughly $72,000. Boxes 3 and 5 would still reflect the full $80,000, because Social Security and Medicare tax applied to those deductions.

Box 12 Codes That Affect Taxable Income

Box 12 can hold up to four entries, each labeled with a letter code. Some codes flag amounts that were removed from Box 1; others are informational only. The ones most likely to matter when you’re checking your taxable income:

Code D — traditional 401(k) elective deferrals. Excluded from Box 1.⁷
Code E — 403(b) salary reduction contributions. Excluded from Box 1.
Code W — health savings account contributions made by you through payroll or by your employer. Excluded from Box 1.
Code AA — designated Roth 401(k) contributions. Unlike Code D, this amount is included in Box 1 because Roth contributions are after-tax.
Code DD — total cost of your employer-sponsored health coverage. This is informational and does not increase your tax liability; the IRS requires the reporting so you can see the true cost of your health benefits.¹⁰

If Code DD looks alarmingly large, it combines what your employer paid and what you paid toward health coverage. It is not taxed.

Multiple W-2s, Allocated Tips, and Other Special Cases

If you worked for more than one employer, you’ll get a separate W-2 from each. Add every Box 1 figure together and enter the total on line 1a of Form 1040.¹ The IRS receives copies of all your W-2s and will flag a return that doesn’t reconcile.

Multiple employers also create a Social Security wrinkle. Each employer withholds 6.2% on the first $184,500 independently. If your combined wages exceed the cap, you’ll have too much Social Security tax withheld and can claim the excess as a credit on your return. If instead a single employer over-withheld through a payroll error, you can’t claim that on your return; ask the employer to correct it, and if they refuse, file Form 843 with the IRS.¹¹

Tipped workers should look at Box 8. Allocated tips are amounts your employer assigned to you when total reported tips for the staff fell below a set percentage of gross receipts. They are not included in Boxes 1, 3, or 5, and no taxes were withheld on them. You generally must report allocated tips as income on your return unless you have records proving your actual tips were lower, and you’ll use Form 4137 to figure Social Security and Medicare tax on unreported tips.¹² The IRS knows the Box 8 figure and expects it on your return.

When Box 1 Looks Wrong or Your W-2 Never Arrives

Employers must deliver W-2s by January 31 of the year after the tax year, so 2026 earnings should be in hand by January 31, 2027.¹³

If a number looks off, ask your payroll department for a corrected form, called a W-2c. Employers are required to provide the W-2c as soon as possible after filing the correction with the Social Security Administration.¹⁴

If your W-2 never shows up or your employer won’t correct it, call the IRS at 800-829-1040 after the end of February. Have the employer’s name, address, and phone number ready, along with your dates of employment and an estimate of your wages. The IRS will contact your employer and send you Form 4852, a substitute W-2.¹⁵ Filing with Form 4852 may delay your refund while the IRS verifies the information, and if a corrected W-2 arrives later with different figures, you’ll amend using Form 1040-X.¹⁶

1
Internal Revenue Service. Form 1040 (2025)
2
Internal Revenue Service. Group-Term Life Insurance
3
Internal Revenue Service. Retirement Plan FAQs Regarding Contributions
4
Social Security Administration. Contribution and Benefit Base
5
Internal Revenue Service. Topic No. 751, Social Security and Medicare Withholding Rates
6
Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026
7
Internal Revenue Service. General Instructions for Forms W-2 and W-3 (2026)
8
Internal Revenue Service. Expanded Availability of Health Savings Accounts Under the One, Big, Beautiful Bill Act (OBBBA) Notice 2026-5
9
Internal Revenue Service. Publication 15-B
10
Internal Revenue Service. Reporting Employer-Provided Health Coverage on Form W-2
11
Internal Revenue Service. Topic No. 608, Excess Social Security and RRTA Tax Withheld
12
Internal Revenue Service. Form 4137 (2025)
13
Office of the Law Revision Counsel. 26 USC Subtitle F, Chapter 61, Subchapter A, Part III, Subpart C – Information Regarding Wages Paid Employees
14
Social Security Administration. Helpful Hints to Forms W-2c/W-3c Filing
15
Internal Revenue Service. Form 4852 – Substitute for Form W-2, Wage and Tax Statement
16
Internal Revenue Service. W-2 – Additional, Incorrect, Lost, Non-Receipt, Omitted