Payroll Taxes: The Tax Most People Don't Notice

How payroll taxes are structured differently from income tax, and why most workers underestimate how much they actually pay.

Look at a typical paycheck and there’s usually a line for income tax withholding, discussed in the tax brackets lesson elsewhere in this module - and a separate, smaller-looking line labeled something like FICA. That second line is the payroll tax, and despite getting far less attention than income tax, it’s often the larger tax bill for a typical worker, especially earlier in their career.

What payroll taxes actually fund

In the United States, payroll taxes are formally called FICA taxes, short for the Federal Insurance Contributions Act, and they fund two specific programs directly: Social Security, covered in its own lesson elsewhere in this module, and Medicare. Unlike income tax, which funds general government spending and can, in principle, go toward almost anything Congress decides, payroll tax revenue is earmarked specifically for these two programs, which is part of why it’s structured so differently from income tax.

Why it’s structured differently

Payroll tax is charged as a flat percentage of wages - currently 6.2% for Social Security and 1.45% for Medicare, deducted directly from an employee’s paycheck - rather than the graduated, bracket-based structure used for income tax. It also applies starting from the very first dollar earned, with no equivalent of income tax’s standard deduction reducing the amount subject to tax. This is why a lower-income worker, who might owe relatively little income tax after deductions and credits, can still find payroll tax to be their single largest tax bill.

A paycheck where payroll tax outweighs income tax

Imagine a worker earning $35,000 a year. After the standard deduction, their federal income tax bill might come to roughly $1,500. Their payroll tax, by contrast, applies to the full $35,000 with no deduction: 7.65% combined for Social Security and Medicare comes to about $2,678. For this worker, payroll tax is nearly double their income tax bill - a pattern common for many low- and middle-income workers, even though payroll tax rarely gets discussed with anywhere near the attention income tax receives.

The wage base limit and the employer match

Social Security’s portion of payroll tax has a wage base limit - an income threshold above which no additional Social Security tax is owed for the rest of the year, adjusted annually. A worker earning well above this threshold pays Social Security tax on only part of their income, which is part of why payroll tax, taken as a share of total income, tends to fall as income rises - the opposite pattern from the progressive structure of income tax. Medicare’s tax, notably, has no equivalent wage base limit and applies to all earnings.

Employers also owe payroll tax on each employee’s wages, called the employer match - typically matching the employee’s 7.65% with an equal contribution of their own, meaning the true cost of Social Security and Medicare funding on a given wage is roughly double what appears on the employee’s own pay stub.

Assuming the employer's half of payroll tax doesn't affect the employee at all

Many economists argue that even though the employer technically pays half of payroll tax directly, the real economic burden still largely falls on the employee - in the form of lower wages than the employer would otherwise offer, since the employer accounts for its total labor cost, tax included, when setting pay. Who legally writes the check and who actually bears the cost aren't necessarily the same, a distinction covered more generally in the tax incidence lesson.

Key takeaways

Payroll tax, formally FICA, funds Social Security and Medicare specifically, unlike general-purpose income tax.
It's charged as a flat percentage from the first dollar earned, with no deduction reducing the taxable amount.
For many lower- and middle-income workers, payroll tax exceeds their income tax bill.
The Social Security wage base limit means high earners pay the tax on only part of their income.
Employers match employee payroll tax contributions, roughly doubling the true cost tied to each wage.
Many economists believe employees ultimately bear the cost of the employer's share too, through lower wages.