IRS may legitimately ask for taxpayer ID verification with Letter 5071C
In 2015, we first reported a new method the IRS was using to verify the identity of taxpayers as part of its effort to combat the growing problem of identity theft. That technique, a mailed letter known as Letter 5071C, asks taxpayers to verify their identity in order to complete processing of their return if the taxpayer did file it or reject the return if the taxpayer did not file it.
These 5071C letters are still being used, and may be mailed to taxpayers (see image for a sample of an 
authentic Letter 5071C). If you ever had any questions about the authenticity of an IRS communication, either mailed, phoned or emailed, or if you wonder how to respond to an IRS communication, please contact your ShindelRock tax professional.