you may need previous year's data for this year's tax return

Here is something from Internet:

Q: How far back can I request a copy of a past tax return?

A: Typically, you can request copies of Tax Forms 1040, 1040A, and 1040EZ for up to 6 years ago (before they’re destroyed by law). Copies of other types of tax forms may be available for longer than 6 years.