Final answer:
The factor that determines whether Social Security benefits received by a taxpayer are tax free is the taxpayer's income from all sources.
Step-by-step explanation:
The factor that determines whether Social Security benefits received by a taxpayer are tax free is option c: the taxpayer's income from all sources. The amount of income a taxpayer receives from all sources, including Social Security benefits, determines whether they are subject to federal income tax. If the taxpayer's income is below a certain threshold, their Social Security benefits may be tax-free.
For example, if a taxpayer's income from all sources is below $25,000 for individuals or $32,000 for joint filers, their Social Security benefits are tax-free. However, if their income exceeds these thresholds, a portion of their benefits may be subject to taxation.
It's important for taxpayers to understand their specific situation and consult a tax professional or the IRS guidelines to determine the taxability of their Social Security benefits.