USC's renovation of the Coliseum will place luxury boxes atop a large swath of seats near midfield, add aisles and concourses and shrink the stadium's capacity from 94,000 to 77,500.
The alterations mean many season-ticket holders will be forced to move.
USC began its rollout of the re-seating process with a video featuring football coach Clay Helton and athletic director Lynn Swann on Monday. In it, Swann said that USC staffers would contact every season-ticket holder or member of the Trojan Athletic Fund individually, over 15 months, to work through the process.
One third of the seats would require an extra fee, what Swann called "a one-time Coliseum restoration gift."
"We will do our utmost to make this process as fair as possible," Swann said. "And we know in many cases you have had season tickets in the same location for years, have become close friends with those sitting near you and do not want anything to change. But, unfortunately, the change will come."
The $270-million renovation — what Helton called "a glorious update" — is scheduled to begin after the 2017 season and be completed in time for the start of the 2019 season.
The renovation also will replace every seat in the stadium, restore the peristyle and improve infrastructure.
USC has said that student seats would not be moved.
Swann did not say how many season-ticket holders would be affected or the cost of the required one-time "gift" to secure a season seat. He said season-ticket holders would receive a detailed re-seating guide in the near future.