The two parties have not been in contact over a new deal since August, Goal has revealed.
The 25-year-old will be free to speak with foreign clubs on January 1.
Given Christensen is enjoying career best form, it is likely a number of suitors will be calling his agent in the winter.
The Dane wants to remain in west London, but he is displeased with Chelsea's most recent offer as it would make him one of the lowest paid players at the club.
It is not the only contract stand-off giving Thomas Tuchel a massive headache at the moment.
Both centre-backs have become vitally important for Tuchel and the club would loathe to lose them for free next summer.
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