I received a letter 50171c from the irs to confirm my identity. What does that mean ?

[JohnW15]

The 5071C letter means that the IRS has received your return, but needs more information from you to verify your identity.

You can do either of the following:

• Go to Identity Verification Service and follow the online instructions.
• Call the IRS toll-free on 800-830-5084 for Identity Verification.

For either option, you’ll need a copy of your prior year tax return, current return, and supporting documents like W-2s, 1099s, or Schedule C. 

If you didn’t file the return in question, choose either option to notify the IRS.