Why Your Pay Stub Matters
Your pay stub is a detailed record of every dollar your employer allocated to you during the pay period, and every dollar that left before it reached your bank account. Most employees look only at the bottom line — net pay — and ignore the rest. That's a mistake.
Payroll errors happen more than most people realize. Incorrect tax withholding, missed deductions, wrong benefit amounts, and pay rate errors all show up as quiet discrepancies on a pay stub that go unnoticed for months or years. Employees who understand their stubs catch these faster.
Beyond error detection, understanding your stub helps you make informed decisions. Do you know whether your 401k contribution is pre-tax or Roth? Are you maximizing your FSA? Is your W-4 withholding set correctly to avoid a surprise tax bill? All of that information lives on your pay stub.
Gross Pay: Your Starting Number
Gross pay is the total compensation you earned before any deductions. It is the top-line number — your hourly rate times hours worked, your annual salary divided by pay periods, or your base salary plus any additional compensation for the period.
Types of gross pay you may see
Regular pay: Your standard wages for the period — base salary or regular hourly rate times straight-time hours worked.
Overtime pay: Hours worked beyond 40 per week for non-exempt employees, paid at 1.5x your regular rate under the Fair Labor Standards Act (some states have stricter rules). Overtime is listed separately on most stubs.
Bonus or commission: Performance-based compensation, often listed as a separate line item in the pay period it is paid. Bonuses are typically taxed at a supplemental withholding rate of 22% at the federal level.
Imputed income: Non-cash benefits that are taxable — for example, employer-paid life insurance above $50,000 face value, or certain personal use of a company vehicle. These increase your taxable income even though you receive them as a benefit, not cash.
Federal Income Tax Withholding
Federal income tax withholding is the amount your employer sends to the IRS on your behalf each pay period. This is an advance payment toward your annual income tax bill — the actual amount you owe is calculated when you file your tax return.
The withholding amount depends on three factors: your gross pay, your pay frequency (weekly, bi-weekly, semi-monthly, monthly), and the elections you made on your W-4 form. If your W-4 is set incorrectly, you could be withholding too much (interest-free loan to the government, large refund) or too little (a tax bill plus potential underpayment penalty in April).
Your W-4 determines withholding using the IRS's income tax brackets. The more allowances or adjustments you claim, the less is withheld. The right setting is one where your withholding closely matches your actual tax liability — neither a large refund nor a large bill.
If your life changed significantly this year (married, had a child, started a side business, changed jobs), review your W-4 with the IRS withholding estimator at irs.gov to make sure your withholding is calibrated correctly.
State and Local Income Tax
Most states impose their own income tax, which your employer withholds separately from federal tax. The rate varies dramatically by state — from 0% in states like Florida, Texas, and Washington to over 13% at the top bracket in California.
You typically complete a state equivalent of the W-4 (sometimes called a withholding certificate) when you start a job. Some states use the same elections as your federal W-4; others have their own forms.
Local income taxis a line that surprises many employees. Some cities and counties impose their own income tax — New York City, Philadelphia, and Columbus, Ohio are notable examples. If you live or work in one of these jurisdictions, you'll see a local tax line on your stub.
If you moved to a new state or city this year, make sure your employer has your correct address on file and that local tax withholding is set up properly. Working remotely while living in a different state from your employer can create multi-state tax obligations that require careful handling.
FICA: Social Security and Medicare
FICA stands for the Federal Insurance Contributions Act. These two taxes fund Social Security and Medicare and are mandatory for nearly all employees. Unlike income tax, there is no withholding form to adjust — the rates are fixed by law.
Social Security tax
The Social Security tax rate is 6.2% of your gross wages, up to the annual wage base (which adjusts each year — in 2025 it was $176,100). If you earn more than the wage base, you stop paying Social Security tax on wages above that threshold. Your employer matches your 6.2% contribution, so the total Social Security tax paid on your wages is 12.4%.
Medicare tax
The Medicare tax rate is 1.45% of all wages — there is no wage cap. For high earners, an additional 0.9% Additional Medicare Tax applies to wages above $200,000 ($250,000 for married filing jointly). Your employer matches the standard 1.45% but not the 0.9% surcharge.
Combined, you pay 7.65% of your gross wages in FICA taxes (up to the Social Security wage base), and your employer pays the same amount. This is why your total compensation cost to your employer is higher than your gross pay — employer FICA contributions add roughly 7.65% on top of your wages.
Pre-Tax Deductions: 401k and Benefits
Pre-tax deductions are amounts subtracted from your gross pay before income taxes are calculated. This reduces your taxable income — meaning you pay less income tax in the current year. These are among the most valuable lines on your stub.
Traditional 401k contributions
If you contribute to a traditional (pre-tax) 401k, the contribution reduces your taxable income dollar for dollar. A $500/month 401k contribution at a 22% marginal tax rate saves you $110/month in federal income taxes — meaning your take-home pay only drops by $390, not $500. The contribution limit for 2025 is $23,500 ($31,000 for those 50 and older with catch-up contributions).
Health, dental, and vision insurance premiums
If your health insurance premiums are paid through a Section 125 cafeteria plan (most employer plans are), your share of the premiums is deducted pre-tax. This reduces both your income tax and your FICA taxes, making employer-provided health insurance one of the most tax-advantaged benefits available.
FSA and HSA contributions
Flexible Spending Account (FSA) and Health Savings Account (HSA) contributions are also pre-tax. FSAs allow up to $3,300 (2025) for healthcare expenses; HSAs allow $4,300 for individuals or $8,550 for families with a qualifying high-deductible health plan. Both reduce your taxable income; HSA contributions also roll over indefinitely and can be invested, making them a powerful long-term savings vehicle.
Dependent care FSA
If you have children in daycare or care for an eligible dependent, a Dependent Care FSA lets you set aside up to $5,000 pre-tax for qualifying care expenses. This is often one of the most underutilized tax benefits available to working parents.
Post-Tax Deductions
Post-tax deductions come out of your pay after all taxes have been calculated. They reduce your net pay but not your taxable income.
Roth 401k contributions: Unlike traditional 401k, Roth contributions are made with after-tax dollars. You get no tax deduction now, but qualified withdrawals in retirement are completely tax-free. Roth is often better for people who expect to be in a higher tax bracket in retirement.
Voluntary benefits: Some employer-offered benefits — supplemental life insurance, disability insurance above the employer-provided base, accident or critical illness coverage, legal services plans — may be deducted post-tax depending on how the plan is structured.
Wage garnishments: Court-ordered deductions for child support, alimony, or debt judgments appear here. If you see an unfamiliar garnishment line, contact your HR department immediately for documentation.
Net Pay: What You Actually Take Home
Net pay — also called take-home pay — is gross pay minus all taxes and deductions. It is the amount that lands in your bank account each pay period.
For a concrete example: an employee earning $75,000/year paid bi-weekly (26 pay periods) has a gross pay of $2,884.62 per period. After federal tax (~$336), state tax (~$130, varies by state), Social Security ($178.85), Medicare ($41.83), a traditional 401k contribution ($300), and health insurance premiums ($125), their net pay might be approximately $1,773 — about 61% of gross pay.
Use the paycheck calculator to model your own numbers — change your 401k contribution, adjust your W-4 withholding, or compare bi-weekly to semi-monthly pay and see exactly how each change affects your take-home pay. For salary vs. hourly comparisons, the salary-to-hourly calculator shows your equivalent hourly rate and estimated take-home at different income levels.
Common Mistakes and What to Check
Now that you can read every line, here are the most common errors and issues to watch for on each stub.
Incorrect pay rate
If you received a raise, verify your first few stubs after the change to confirm the new rate is reflected. Payroll systems sometimes lag or apply retroactive changes incorrectly. Small errors compounded over a full year add up quickly.
Missing overtime
Non-exempt employees must be paid 1.5x for hours over 40 in a workweek. If you worked extra hours and they appear as regular pay, that is a wage and hour violation. Keep records of your hours to cross-reference against your stub.
Wrong 401k contribution amount
Check that your elected contribution percentage is correctly reflected. If you changed your contribution election, verify it took effect on the correct pay period. Missed contributions early in the year mean missed employer match — free money left on the table.
YTD totals exceeding limits
Your pay stub should show year-to-date (YTD) totals for each line. Check that your 401k YTD total does not exceed the annual IRS limit. Similarly, Social Security tax should stop being withheld once your YTD wages exceed the Social Security wage base — if it continues, contact payroll.
Unexpected deductions
Any line you do not recognize is worth investigating. Ask your HR or payroll department for an explanation of any unfamiliar code or amount. Do not assume unexplained deductions are correct — they frequently are not.