Payroll taxes are levied on your gross wages, before deductions

Payroll taxes — Social Security, Medicare, and federal income tax withholding — are calculated on your gross pay, which is the total amount your employer pays you before anything comes out. This includes your base salary or hourly wage, plus bonuses, commissions, overtime pay, and certain other forms of compensation. The tax is taken from your paycheck before you see the money.

The key point: payroll taxes are based on what you earn, not on what you take home. If you earn $1,000 in a week, payroll taxes are calculated on that full $1,000, even though you might receive only $750 after taxes and other deductions are removed.

Key Takeaways

  • Social Security and Medicare taxes are calculated on your gross wages up to an annual earnings cap that changes each year.
  • Federal income tax withholding is calculated on your gross pay, but the amount withheld depends on your W-4 form and tax bracket.
  • Bonuses, commissions, overtime, and certain fringe benefits count as wages subject to payroll tax.
  • State and local income taxes, where they exist, are also calculated on gross wages and withheld separately from federal payroll taxes.

Social Security and Medicare tax bases

Social Security tax is calculated on all wages up to a maximum annual amount. This cap changes each year — it is adjusted based on wage growth in the economy. Once you reach that cap in a calendar year, your employer stops withholding Social Security tax from your paychecks for the rest of that year. Medicare tax, by contrast, has no cap: it is calculated on all your wages, no matter how much you earn.

Both taxes are split between you and your employer. You pay 6.2% for Social Security and 1.45% for Medicare; your employer pays the same amounts. If you are self-employed, you pay both the employee and employer portions, which totals 15.3% for these two taxes combined.

Federal income tax withholding

Federal income tax withholding is also based on your gross pay, but the amount withheld depends on information you provide on your W-4 form. The W-4 tells your employer how much to withhold based on your expected tax liability for the year. The more dependents or other deductions you claim on the form, the less your employer withholds. The less you claim, the more is withheld.

Your employer uses IRS withholding tables to calculate the amount based on your pay frequency (weekly, biweekly, monthly) and the information on your W-4. This withholding is an estimate — it is meant to cover your federal income tax bill for the year, but the actual amount you owe is determined when you file your tax return.

Bonuses, commissions, and overtime

Any additional pay beyond your regular wages is subject to payroll tax. This includes performance bonuses, sales commissions, overtime pay, and shift differentials. These are all considered wages and are taxed the same way as your regular pay.

Some employers use a flat withholding rate for bonuses — often 22% or 37% federal income tax, depending on the bonus amount — rather than calculating based on your W-4. This is a simplified method allowed by the IRS, though the actual tax owed may differ. The difference is settled when you file your annual tax return.

Fringe benefits and taxable compensation

Most fringe benefits — like health insurance premiums your employer pays on your behalf — are not subject to payroll tax. However, some benefits do count as taxable wages. These include certain bonuses, cash allowances, and non-may have access to deferred compensation plans.

For example, if your employer provides a car allowance or pays for a gym membership as a taxable benefit, that amount is added to your gross wages and subject to payroll tax. Your employer should tell you which benefits are taxable and include them in your gross pay on your pay stub.

State and local income taxes

If you live or work in a state or city with an income tax, those taxes are also calculated on your gross wages. The withholding works similarly to federal income tax: your employer withholds an amount based on forms you complete (often a state W-4 or equivalent). The rates and rules vary by state and locality.

Some states have no income tax at all, so residents of those states have no state income tax withheld. Others have a flat tax rate, while still others use a progressive system with multiple brackets. Your pay stub should show federal, state, and local withholding separately.

What does not count as wages for payroll tax

Certain payments are not subject to payroll tax, even though they come from your employer. These include reimbursements for business expenses (if properly documented), certain health insurance premiums, contributions to traditional 401(k) plans, and some other pre-tax deductions. These reduce your taxable wages.

For example, if you contribute $200 per paycheck to a 401(k), that $200 is subtracted from your gross pay before Social Security and Medicare taxes are calculated. However, federal income tax withholding is calculated on a slightly different base that includes some of these deductions, which is why your federal withholding may not match your Social Security and Medicare withholding exactly.

Frequently Asked Questions

Are payroll taxes calculated before or after my 401(k) contribution?

Social Security and Medicare taxes are calculated before your 401(k) contribution is removed, so they explore to your full gross pay. Federal income tax withholding is calculated on a base that excludes your 401(k) contribution. This is why your federal withholding may be lower than it would be if calculated on your full gross pay.

If I get a bonus, is payroll tax calculated the same way as on my regular pay?

Yes, bonuses are subject to the same payroll taxes as regular wages. However, employers often use a flat withholding rate for bonuses instead of calculating based on your W-4. The actual tax owed is determined when you file your return, and you may receive a refund or owe additional tax depending on your total income for the year.

What happens if I reach the Social Security wage cap?

Once your earnings reach the annual cap, your employer stops withholding Social Security tax from your remaining paychecks for that year. Medicare tax continues to be withheld on all wages. The cap changes each year and is announced by the Social Security Administration in October.

Do I pay payroll taxes on tips?

Yes, tips are considered wages and are subject to payroll tax. You are required to report tips to your employer, and they will include them in your gross pay for tax withholding purposes. If you do not report tips, you may face penalties and back taxes.

Are employer-paid health insurance premiums subject to payroll tax?

No, most employer-paid health insurance premiums are not subject to payroll tax. They are deducted from your pay before taxes are calculated. However, if your employer provides a taxable benefit like a cash allowance in place of insurance, that amount is subject to payroll tax.