Cal. Pen. Code § 2933.6
The Department of Corrections and Rehabilitation shall, no later than July 1, 2017, establish regulations to allow specified inmates placed in segregation housing to earn credits pursuant to Section 2933 or 2933.05, or credits as otherwise specified in regulation, during the time he or she is in segregation housing. The regulations may establish separate classifications of serious disciplinary infractions to determine the rate of restoration of credits, the time period required before forfeited credits or a portion thereof may be restored, and the percentage of forfeited credits that may be restored for those time periods, not to exceed those percentages authorized for general population inmates. The regulations shall provide for credit earning for inmates who successfully complete specific program performance objectives.
Ca. Pen. Code § 2933.6