Tottenham will bank 10 percent of the transfer fee if Gylfi Sigurdsson completes his move from Swansea to Everton, sources have told ESPN FC.
Sigurdsson joined Swansea from Tottenham in the part-exchange deal that took Ben Davies and Michel Vorm to White Hart Lane three years ago, with Spurs negotiating the 10 percent sell-on clause for the Iceland international.
Tottenham have a similar arrangement with Swansea over Tom Carroll, who moved to the Liberty Stadium in January.
Everton are reportedly closing in on signing Sigurdsson, who was valued at around £10 million by Tottenham when he left the club in 2014, after agreeing a deal with Swansea worth up to £45m for the playmaker. Sigurdsson is reportedly due to undergo a medical on Wednesday before sealing the move.
The deal could also boost Tottenham's hopes of signing Everton midfielder Ross Barkley.
A separate source has told ESPN FC that Spurs have held extensive talks with the representatives of the England international, and are confident of reaching an agreement.
But they remain some way from a deal with Everton for Barkley, who has one year remaining on his contract and is facing a spell on the sidelines with a hamstring injury.