Ask software provider or tax preparer
Those who need a copy of their tax return should check with their software provider or tax preparer first. Prior-year tax returns are available from the IRS for a fee.
Get a transcript
Taxpayers who can’t get a copy of a prior-year return may order a tax transcript from the IRS. To protect taxpayers’ identities, this document partially masks personally identifible information such as names, addresses and Social Security numbers. All financial entries, including the filer’s adjusted gross income, are fully visible. These are free and available for the most current tax year after the IRS has processed the return. People can also get them for the past three years.
Taxpayers ordering a transcript should allow time for delivery. Here are the three ways to get transcripts:
Request a copy of a tax return from the IRS
If necessary, taxpayers can request a copy of a tax return by completing and mailing Form 4506 to the IRS address listed on the form. There’s a $50 fee for each copy and these are available for the current tax year and up to six years prior.
Illinois
Taxpayers can get a copy of IL returns through MyTaxIL.
https://www2.illinois.gov/rev/questionsandanswers/Pages/50.aspx