What is California Law in regards to timely tilling of health insurance claims to Blue Cross and Blue Shield. Is there a statute of limitation?

Insurance is a private contract between the provider and the insured. While states do regulate certain aspects of the insurance industry, there isn't a law regarding the filing of claims to insurance companies. You need to find out what your policy says. Typically, claims need to be filed before March 31st of the year after the service was provided.

Statute of Limitations have to do with law suits, not private contracts.