The certificate of acknowledgment (PDF) must be in the form set forth in California Civil Code section 1189. Tell the court that the other party received a summons or other legal papers in a civil case that were delivered to (served on) that party.The sample acknowledgement letters for receipt of payment provided below can be used as format templates for official and personal purposes. Hi (Recipient's name), I'm contacting you to acknowledge your payment of (amount) for (the product or service they have purchased). Upon receipt, the individual has 20 days to complete, sign, and return the notice and acknowledgement. How do you fill out an acknowledgment letter? Judicial Council Form POS-015 is required to be used as the Notice and Acknowledgment of Receipt.