The sample acknowledgement letters for receipt of payment provided below can be used as format templates for official and personal purposes. What do you need to include in your donation acknowledgment letter?An acknowledgement agreement is a legal document formalizing some agreement between parties, similar to a memorandum of understanding. Thank you for your prompt payment. It is very important that you complete this form, have it notarized, and return it to our office, even if no direct payments were received. How do you fill out an acknowledgment letter? Contribution Plan. Policy. Click on your admission type below to find out how to complete orientation. An Acknowledgment of Paternity (AOP) is a legal document that allows parents who aren't married to establish legal paternity. Title Money Receipt.