Write to the IRS and ask for copies of your personal and/or business transcripts. Mail your letter to your local IRS office of IRS Service Center addressed Attention: Taxpayer Service. you’ll find these addresses in your local phone book. In the letter include your name, address, social security number or employer identification number, and the tax years or periods in question.
You can also request a transcript online at https://www.irs.gov/individuals/get-transcript
If you’re not sure what tax years or periods are in question (this is common), you should ask for more years or periods of time to cover all time frames of concern to make sure you get all the information you need. This will help you avoid any surprises down the road for those years or periods you failed to ask about. You want the IRS to disclose to you everything they have about you.