The Internal Revenue Service Publication 17 includes a chart of federal income tax liability by filing status and taxable income up to $100,000 for 2014. Marginal tax rates ranged from 10 percent to 39.6 percent for 2014, according to efile.com.
IRS Publication 17 states tax liability by income up to $100,000 for each filing status and directs filers to the 2014 Tax Computation Worksheet for taxable income over $100,000. Thresholds for each tax bracket vary by filing status. The lowest rates are charged to head of household filers, and the highest rates are charged to single filers, according to Forbes. Head of household taxable income up to $18,750 was subject to the 10-percent rate in 2014, while only the first $9,225 of a single filer's income was taxed at the 10-percent rate.
IRS Publication 501 states that a person filing as head of household must be unmarried or considered unmarried for tax purposes and must be responsible for half the costs associated with keeping a home and have a qualifying person, such as a minor dependent child, living in the home for at least half of the tax year. Other unmarried taxpayers file taxes as single people, and married people may file either joint or separate returns.