The 21-year-old is currently in his third season on loan at Atletico Madrid, where he has been in impressive form.
The Belgium international, who is wanted by Atletico on a permanent deal, is willing to return to Chelsea, but wants assurances that he will play first-team football.
"I know that [Atletico] want to make an effort [to sign me], but it depends on Chelsea, on what they want and how much they are going to ask," Courtois told La Sexta.
"First my agent is going to talk with Chelsea to see when I can speak with someone there, and from there we can take another step."
Courtois joined Chelsea from Genk in 2011.