January 1st is the default fiscal method for all taxpayers in the US. Business entities can choose to use their fiscal year as their tax year when they incorpo

January 1st is the default fiscal method for all taxpayers in the US. Business entities can choose to use their fiscal year as their tax year when they incorporate/charter. Individuals can also choose a non-calendar year tax year, but only before they file their first tax return. All US taxpayers can change their tax year by petitioning the IRS for a change of taxable year; this is usually granted without hassle for businesses (i.e, C-Corporations), but almost never for individuals.