Did you receive a letter from the IRS explaining what to do to verify your identity?  If you did, you need to follow the instructions on the letter.  If you receive a 5071C letter, verify your identity with the IRS. There are two ways to verify your identity with the IRS: Online on the IRS' secure Identity Verification Service website, idverify.irs.gov or. By calling the toll-free number listed in your letter.

Identity Verification for IRS Letter Recipients

https://www.irs.gov/identity-theft-fraud-scams/identity-verification-for-irs-letter-recipients