Cal. Rev. & Tax. Code § 6381

There are exempted from the computation of the amount of the sales tax the gross receipts from the sale of any tangible personal property to:

(a)The United States, its unincorporated agencies and instrumentalities;

(b)Any incorporated agency or instrumentality of the United States wholly owned by the United States or by a corporation wholly owned by the United States;

(c)The American National Red Cross, its chapters and branches.