Reading a W-2 Box by Box
Anthony came in the second week of February with a white envelope from Amazon.
He slid it across the desk. “W-2,” he said. “Same every year.”
The preparer picked it up and started reading. Not skimming — reading. Left to right, top to bottom, every box.
Box 1: $52,400. Box 2: $5,890. Box 12a: D — $2,600. Box 12b: DD — $6,240. Box 14: RSU — $1,200.
“Anthony,” she said, “did you receive any stock this year from Amazon?”
He blinked. “Oh — yeah. They gave me some RSUs. Is that important?”
“Yes,” she said. “It’s already in Box 1. But we need to make sure we handle it correctly on the return.”
She had found something by reading the W-2 carefully. That’s the job.
The W-2 is the most common document in tax prep. You will see hundreds of them over a career. Most beginners glance at Box 1 and Box 2 and think they’re done. Experienced preparers read every box because every box is telling them something. This lesson teaches you to read a W-2 the way a professional does — completely.
Form W-2, Wage and Tax Statement, is the document employers are legally required to send to every employee by January 31 of the following year. It reports what the employee earned and how much was withheld for federal taxes, Social Security, Medicare, and in most cases state taxes.
The IRS receives a copy directly from the employer. When your client hands you their W-2, the IRS already has the same numbers. If your return doesn’t match what the employer reported, the IRS will notice. This is why reading the W-2 carefully and entering it accurately is not optional.
Box 1 — Wages, Tips, Other Compensation. This is the federal taxable wage amount. It is NOT the same as what the employee was paid. Pre-tax deductions — traditional 401(k) contributions, health insurance premiums, HSA contributions — have already been subtracted. If Anthony earned $55,000 but contributed $2,600 to his 401(k), Box 1 shows $52,400. This number goes on Line 1a of the 1040.
Box 2 — Federal Income Tax Withheld. The total federal income tax the employer sent to the IRS on the employee’s behalf throughout the year. This is the client’s main pre-payment. A higher Box 2 relative to their tax liability means a larger refund. A lower Box 2 means they may owe. This goes on Line 25a of the 1040.
Box 3 — Social Security Wages. The wages subject to Social Security tax (6.2%). Usually higher than Box 1 because pre-tax health insurance and FSA deductions reduce Box 1 but not Box 3, while 401(k) contributions reduce both. The 2025 Social Security wage base is $176,100 — wages above that are not subject to the Social Security portion of FICA.
Box 4 — Social Security Tax Withheld. Should be exactly 6.2% of Box 3, up to the wage base limit. If it’s not, flag it. An employer error here is uncommon but real.
Box 5 — Medicare Wages and Tips. All wages subject to Medicare tax (1.45%). No wage base cap. Employees earning over $200,000 ($250,000 for MFJ) also pay an additional 0.9% Additional Medicare Tax.
Box 6 — Medicare Tax Withheld. Should be 1.45% of Box 5. On high earners you may see the additional 0.9% reflected here as well.
Box 12 contains letter codes followed by dollar amounts. Each code means something specific. We cover the most important codes in Lesson 3, but here’s what you need to know right now: look at Box 12 on every W-2. The codes tell you about retirement contributions, employer-paid benefits, and sometimes income you need to handle specially.
Anthony’s W-2 shows:
12a: D — $2,600 — traditional 401(k) contribution. Pre-tax. Already excluded from Box 1.
12b: DD — $6,240 — employer-sponsored health insurance cost. Informational only. Does not affect the return.
Statutory Employee. If checked, the client is treated as self-employed for certain purposes. Their income goes on Schedule C, not Line 1a. Rare, but mishandling it is a real error.
Retirement Plan. If checked, the employee participated in an employer retirement plan this year. This affects whether they can deduct a traditional IRA contribution. If Box 13 is checked and their income exceeds certain thresholds, the IRA deduction phases out. Always check Box 13 before discussing IRA deductibility.
Third-Party Sick Pay. Sick pay received from an insurer rather than the employer. Sometimes creates a discrepancy in Social Security and Medicare amounts. Flag it and verify.
Box 14 is a free-form information box. Employers use it to report things like union dues, state disability insurance, restricted stock unit (RSU) income, educational assistance, and other items. The label and meaning vary by employer. Some Box 14 items affect the return; most are informational.
Anthony’s Box 14 shows RSU — $1,200. This means Amazon reported $1,200 of restricted stock unit income in his wages. It’s already included in Box 1. But it tells the preparer to look for a 1099-B because Anthony likely sold those shares and may need to report a capital gain or loss. More on that in Module 7.
The bottom section of the W-2 covers state and local taxes. We cover these in depth in Lesson 6. The basics: Box 15 is the state employer identification number, Box 16 is state wages, Box 17 is state income tax withheld, and Boxes 18–20 cover local wages and local tax withheld.
For Florida residents who work entirely in Florida, Boxes 15–17 are typically blank or show FL with no amounts. Florida has no state income tax. But if your client worked in another state or lived in Florida and worked remotely for a company in a different state, these boxes matter. We’ll address multi-state situations later in the curriculum.