California Code, Civil Code - CIV § 5655

(a) Any payments made by the owner of a separate interest toward a debt described in subdivision (a) of Section 5650 shall first be applied to the assessments owed, and, only after the assessments owed are paid in full shall the payments be applied to the fees and costs of collection, attorney's fees, late charges, or interest.

(b) When an owner makes a payment, the owner may request a receipt and the association shall provide it.  The receipt shall indicate the date of payment and the person who received it.

(c) The association shall provide a mailing address for overnight payment of assessments.  The address shall be provided in the annual policy statement.