There's a chance that there will be a tie in the final FedEx Cup standings at the conclusion of the Tour Championship at East Lake, and it would mean there would need to be an extra playoff for the FedEx Cup title and its $10 million first-place prize.
The FedEx Cup playoff format is simply sudden death. It's hole-by-hole match play until someone beats the other and wins the $10 million. Second place would get $3 million in the season-long, $35 million bonus pool. In other words, the playoff would be for $7 million. It would also have no bearing on the Tour Championship results.
Since the FedEx Cup was first crowned in 2007, there has not been a playoff for the championship. In addition, since the current format was adopted in 2009, just once (Tiger Woods, 2009) has the No. 1 seed going into the Tour Championship won the FedEx Cup.