Pay stub deductions explained
Deductions on a pay stub fall into three groups: taxes withheld (federal and state income tax, Social Security, Medicare), pre-tax deductions taken before tax is worked out (such as many health premiums and retirement contributions), and after-tax deductions taken afterwards (such as garnishments). Gross pay minus all three is net pay.
Taxes withheld
- Federal income tax, based on your Form W-4.
- Social Security (OASDI) and Medicare — together, FICA.
- State and local income taxes, where they apply.
- State disability or similar contributions in some states.
Pre-tax deductions
Taken before tax is calculated, so they lower your taxable wages. IRS Publication 15-B describes cafeteria (section 125) plans, which let employees choose certain qualified benefits instead of taxable pay. Common examples:
- Health, dental and vision premiums paid through a cafeteria plan.
- Traditional 401(k) contributions (these still count for Social Security and Medicare).
- Health savings account (HSA) and flexible spending account (FSA) contributions.
After-tax deductions
- Roth 401(k) contributions.
- Wage garnishments, such as child support or a court order.
- Some voluntary benefits and union dues.
How it adds up
Net pay = gross pay − taxes − pre-tax deductions − after-tax deductions (+ any reimbursements). Each deduction should appear on its own line so you can check it.
Which deductions are pre-tax depends on the plan and the tax. Your employer or plan documents can confirm how each one is treated.
Sources
- IRS — Publication 15-B, Employer’s Tax Guide to Fringe Benefits
- IRS — Topic no. 751, Social Security and Medicare withholding rates
- IRS — About Form W-4, Employee’s Withholding Certificate
Official sources checked September 23, 2026. This guide explains how pay documents work; it is not tax or legal advice.