Reference

EIN and entity: every page on your EIN record

An employer identification number is the key every return a payer files is matched on: the 941s, the 945, the W-2s and every 1099. The name and EIN on those returns must match the IRS entity record, the record must name the right responsible party, and a vendor's EIN must match its legal name before the 1099 goes out. These are the pages on this site that deal with that record, in one place.