W-2 employment is the most common way American households earn. Understanding the mechanics — how withholding is set, how benefits change the effective compensation, how the timing of pay periods interacts with cash flow — is a working competence, not an HR topic.
- 01Read a W-2 line by line.
- 02Estimate the effective tax rate on marginal earnings from a pay stub.
- 03Compute the value of employer benefits in dollar terms.
The W-2
Box 1 is wages subject to federal income tax. Boxes 3 and 5 are wages subject to Social Security and Medicare. Box 12 lists retirement contributions and other adjustments with letter codes. The three wage numbers rarely match, and the differences are informative.
Withholding
Federal withholding is set by the W-4 form you complete. It approximates your annual tax liability but rarely matches it. If you receive a large refund, you are over-withholding — an interest-free loan to the Treasury. Adjust the W-4 to bring the refund toward zero.
The full compensation
Salary is a fraction of employment income. Employer retirement match, health-insurance premium, life and disability insurance, HSA or FSA contributions, and paid leave add materially. Compute the dollar value once a year; it will change how you negotiate.
- Three wage numbers on a W-2, three different bases.
- A large refund is a cash-flow error, not a windfall.
- Total compensation, not salary, is the number to negotiate.