Gather all prior-year income documents, deductions, credits, and tax records
Download the correct tax forms and instructions for the specific tax year
Use tax software, a tax professional, or paper forms that support prior-year filing
Complete the return using the tax rules and rates for that specific year
Sign and date the return
Attach all required schedules, forms, and copies of W-2s or 1099s
Mail the return to the IRS address listed for that tax year if e-filing is not available
File any required state prior-year tax returns separately
Pay any taxes owed as soon as possible to reduce penalties and interest
Check whether you are due a refund and whether the filing deadline has passed
Keep copies of the filed return and supporting documents for your records