In a phone call today with the Taxpayer Advocate in Philadelphia, I learned that the IRS Service Center in Philadelphia moved, with the final personnel moving into the “new” office in January. The new address is:

Internal Revenue Service
2970 Market St.
Philadelphia, PA 19104

Note that this address should be used only for overnight delivery, courier service, etc.; all other mail to the Philadelphia Service Center should go to the normal address (typically specified in the communication from the IRS).

The Philadelphia Service Center does not process returns; however, they do handle numerous “back-office” tasks including correspondence audits, international adjustments, and many others.