Here are instructions from the IRS to file a 2018 tax return:Tax year 2018 returns must be filed with the IRS center listed on the last page of the current Form 1040 instructions PDF.
Current and prior year tax forms (such as the tax year 2018 Form 1040, 1040-A and 1040-EZ) and instructions are available on the IRS.gov Forms and Publications page or by calling toll-free 800-TAX-FORM (800-829-3676).
However, taxpayers can e-file tax year 2019 and later returns.Taxpayers who are missing Forms W-2, 1098, 1099 or 5498 for the years 2018, 2019 or 2020 should request copies from their employer, bank or other payer.
Taxpayers who are unable to get missing forms from their employer or other payer can order a free wage and income transcript at IRS.gov using the Get Transcript Online tool.