What tax is applied to an employee's earnings for Social Security benefits?

Social Security Tax is directly applied to an employee's earnings to fund the Social Security program, which provides benefits for retirees, disabled individuals, and survivors of deceased workers. This tax is calculated as a percentage of an employee's gross wages up to a certain earnings limit, known as the Social Security wage base limit. The funds collected through this tax are essential for maintaining the Social Security system, which serves as a critical safety net for many Americans during their retirement.

In contrast, the other choices pertain to different types of taxation. Medicare Tax, for example, is specifically used to fund the Medicare program, which provides healthcare for individuals aged 65 and older, while Federal Income Tax pertains to the income tax system based on an individual's tax bracket. State Income Tax is a tax levied by state governments on income earned within that state, which is entirely separate from Social Security. Thus, the Social Security Tax is the correct answer as it directly correlates with employee earnings for funding Social Security benefits.