Comment
Introduced himself as being Mike Wheeler, an IRS investigator, asking me to call him ba ck at this phone number, that is a private landline phone number, ... at extension 221 concerning a file where my name is mentioned. If I do not call back further steps will be taken.
Usually an IRS agent would be calling from his office. Not from a privately owned landline trying to make be believe that it has multible extension numbers sucha as 221; or that does not belong to his own name or wife's name...
I conclude:
A- This guy might be renting an AirBnB flat of the kind and is hiding his true residency from us. Or he is as stupid to use his own landline reveiling to us his true identity by a phone lookup;
B- There is strong evidence that this is potentially an identity verification process that can be sold for 500$ on the dark web and lead to money extorsion of any kind.