Which tax is not withheld from an employee's paycheck?

Sales tax is not withheld from an employee's paycheck because it is a consumption tax imposed on the sale of goods and services, rather than a tax based on an individual's income. Employees typically encounter sales tax when they make purchases, and it is collected at the point of sale by the retailer.

In contrast, federal income tax, state income tax, and Medicare tax are all taxes that are directly deducted from an employee's earnings. Federal income tax is based on the employee's taxable income and is withheld according to the information provided on the employee's W-4 form. State income tax functions similarly, depending on the state in which the employee works. Medicare tax is part of the Federal Insurance Contributions Act (FICA) taxes that support the Medicare program and is also withheld from an employee's gross pay, contributing to their future eligibility for Medicare health benefits.

Therefore, among the options presented, sales tax is the only tax that is not directly deducted from an employee's paycheck.