https://www.irs.gov/newsroom/what-taxpayers-should-know-about-tax-return-copies-and-transcripts order copies of the tax returns for $50/year - Form 4506. Even though they say 6 years, order more years if you need them. 

Actually I have a client in non compliance and I was able to get transcripts back to 2008. They are in the computer, but IRS only begrudgingly will get them. SEND MONEY FOR ALL THE YEARS YOU NEED.