Form 8879 is an electronic signature document that is used to authorize e-filing. It is generated by the software using both the taxpayer's self-selected PIN and the Electronic Return Originator's (ERO's) Practitioner PIN.
Purpose of Form
Form 8879 is the declaration document and
signature authorization for an e-filed return
filed by an electronic return originator (ERO).
Complete Form 8879 when the Practitioner
PIN method is used or when the taxpayer
authorizes the ERO to enter or generate the
taxpayer’s personal identification number
(PIN) on his on his or her e-filed individual income
tax return.
https://www.irs.gov/pub/irs-pdf/f8879.pdf
