Jenson Button says his plans beyond 2016 will be known "soon".
It is strongly rumoured that McLaren-Honda will end its seven-year relationship with the 2009 world champion by replacing him with Stoffel Vandoorne.
Button, 36, has subsequently been linked with a return to Williams.
"I am almost there with my thought process and you will hear about it soon," Button told reporters said Button.
"It will be soon enough. But I’ll tell you this: I will probably be back at Spa in 2017," he added.