Courtois's current deal at Stamford Bridge expires at the end of next season, and he has been repeatedly linked with a move to Real Madrid should Los Blancos miss out on number one target David de Gea.
The 26-year-old has refused to commit his future to the club, instead urging the board to match the spending of Manchester City and Manchester United if they are to convince key players to stay.
"We'll see after the World Cup whether I am a Chelsea player for next year. You see how Manchester City and Manchester United are spending and working," Courtois told reporters.
"If we want to aim for the top, we should do the same - obviously within the limits of what's possible. We'll see what's going on and I am sure the board will do what needs to be done."