Heitinga is entering the final year of his contract and he admits Everton could decide to cash in on him rather than risk losing him for nothing next summer.
Fenerbahce have been linked with a new move for Heitinga after coming close to signing the Dutchman in the January transfer window.
Heitinga admits he has agreed nothing with Everton, but that he could be on the move this summer.
"If they want to earn something for me, this is the moment," Heitinga told Voetbal International. "I have made no arrangement with the club about that.
"I will just wait and see what happens."
Heitinga claimed he was poised for a move to Fernabahce, but that the deal fell through at the final minute because of Everton's valuation.
"Everton asked too much and the deal collapsed," Heitinga said of the proposed move to Fenerbahce.