Cal. Rev. & Tax. Code § 30166

Stamps and meter register settings shall be sold to licensed distributors at their denominated values less a discount of 0.85 percent, which shall be capped at the first one dollar ($1.00) in denominated value. Payment for stamps or meter register settings shall be made at the time of purchase, provided that a licensed distributor, subject to the conditions and provisions of this article, may be permitted to defer payments therefor.