Boateng moved to the Veltins-Arena from Serie A giants Milan in August 2013, with reports suggesting had penned a four-year contract with the Bundesliga side.
However, Schalke chairman Clemens Tonnies stated that the structure of the deal is for it to last three years with the option of a further 12 months.
And he revealed that discussions on a new contract have yet to begin because neither party has suggested they are unhappy with the present situation.
"Kevin-Prince Boateng has a contract with our club that lasts three years," Tonnies told Bild.
"This deal has an option. The contract option implies that the deal will be automatically extended by one campaign if he plays a certain amount of first-team games for Schalke.
"There are currently no talks on a new agreement between Kevin-Prince Boateng and Schalke. Every party has agreed on that."