Cal. Rev. & Tax. Code § 5720.6

“Domicile” means:

(a)The home ranch on January 1 of the current calendar year of the owner of a racehorse or other place where the horse is quartered when not racing or in training to race.

(b)The residence on January 1 of the current calendar year of the owner of any racehorse that is not quartered at a home ranch or other location when not racing or in training to race.