20 C.F.R. § 418.1225
We will consider evidence of your modified adjusted gross income that you provide for a tax year that is more recent than the year described in § 418.1135 (a) or (b) when you meet all of the requirements described in § 418.1201 . We will always ask you for your retained copy of your filed Federal income tax return for the more recent year you request that we use and will use that information to make an initial determination. If you have not filed your Federal income tax return for the more recent year you request that we use, you must provide us with evidence that is equivalent to a copy of a filed Federal income tax return. Evidence that is equivalent to a copy of a filed Federal income tax return is defined in § 418.1265(c) .
20 C.F.R. §418.1225