California Code, Revenue and Taxation Code - RTC § 42101.7

(a) Commencing January 1, 2017, a seller, other than a direct seller, with de minimis sales of prepaid mobile telephony services of less than fifteen thousand dollars ($15,000) during the previous calendar year is not required to collect local charges pursuant to Section 42101.5.  The Department of Finance shall annually review and adjust that de minimis sales threshold as necessary to minimize program administration costs and maintain revenues to support program administration and enforcement activities.  Any adjustment of the de minimis sales threshold shall become operative on January 1 of the following calendar year.  Nothing in this section prevents a seller from collecting and remitting the surcharge on a voluntary basis even if the seller meets the de minimis sales threshold.

(b) For purposes of this section, the de minimis sales threshold shall be based on the aggregate of all sales of prepaid mobile telephone services subject to the local charges at all retail locations operated by the seller and not the individual sales at each retail location operated by the seller.