A business memorandum is a common document that is a sort informal message that is sent from one person in an organization to another in business writing or formal emails. A business memo format is informal and public as well. A memo format should be written keeping the audience needs in mind. The format should have a tone that is formal yet impersonal in nature. The format should be written in common language so that all people can understand the same the subject line should be informative, with the bottom line written at first. It should be clear and concise, and factual with a neutral or positive tone.