Fill out the header information. State clearly who the memo is to, from, the date, and what the memo is regarding. Begin with why the recipient is receiving the memo (the subject).
The first paragraph should be a purpose statement that can be as simple as, "The purpose of this memo is to..."
Include a brief summary of the problem or need you are writing about. The body of the memo should expand on these themes.
State any actions you need the recipient to perform and when you need them performed by.
Close with any follow up items required from the recipients. Also, make sure the ending is courteous and respectful to the readers. Even if you are communicating difficult news remember to do so in a poised and dignified manner.
A business memo also may be a call for action for all team members to become involved in. Writing a business memo is a great tool for leadership teams. Make it short, one page if possible. Bulleted lists are an easy way for the reader to understand the key points of the memo immediately.