According to Forbes, the amount of earnings allowed before taxation begins can vary in any given year. The single factor that affects earning requirements is the filing status.
As of 2014, if a person is filing single in the United States, he is subject to no tax rate if his income lies below $9,075. This is the same for those who are married but filing separately. The requirement increases to $12,950 when filing status changes to head of household and $18,150 for married couples filling jointly or surviving spouses. Forbes notes that these values are what taxpayers use to prepare tax returns in 2014 and 2015.