According to the instructions for that form: "Any taxpayer filing electronically from a home
computer must keep the signed Form PA-8453
and supporting documents for three years after
the due date of the return or the date the return
was filed electronically, whichever is later.
Taxpayers must make the documents available to
the PA Department of Revenue upon request. Do
not mail Form PA-8453 and attachments to the
PA Department of Revenue unless requested."
If you do need to mail in the form, this is the only address listed on the instructions:
PA DEPARTMENT OF REVENUE
BUREAU OF INDIVIDUAL TAXES ELECTRONIC FILING SECTION
PO BOx 280507
HARRISBURG PA 17128-0507
