Once your income reaches a certain threshold, you have to file a federal income-tax return. The income limits depend on your filing status -- single, married, widowed or head of household -- and your age.If you’re 65 or older, the threshold for filing your taxes is higher.f you’re 65 or older, the filing thresholds are higher: -- $10,750 for single filers. -- $13,400 for heads of household. -- $16,150 if you were widowed in 2007 or 2008 and have a dependent child. -- $19,800 for married couples filing jointly in which one spouse is 65 or older.