An informal report, also known as an informal memo, differs from a formal report and doesn't contain such sections as an abstract or executive summary. An informal report is used for internal purposes for business and research and also serves as an outline for a formal report to be written later. An informal report does not have a set length, but should be as brief as possible. However, what is most important is that the writer properly get her message across to the reader.

Write a short outline of what you want to address in your formal report, which is similar to a five-paragraph essay and should include an introduction, body, conclusion and recommendations. Write down the three main points of your argument or proposal, to be used for the body of the report. The outline can just be a quick rundown of ideas that you will address in your report.

Address the report in the top, left corner of the first page and include these elements: to whom the report is going, whom it is from, the date and the subject.

Below that, begin the introduction, the first paragraph of which should be three to five sentences. Answer all of the what, why, when, where and how questions to appropriately address what will be discussed in the body of your report.

Write the body section of your report by using the main points you wrote in your outline. Construct a paragraph for each point of three to five sentences. Make sure these points sufficiently back up the statements you made in your introduction concerning the issues you are addressing in your report.

Write the conclusion, which should reiterate the issues mentioned in your introduction and summarize the main points you addressed in the body of your report. The final sentence of your conclusion should resonate with the reader and show the urgency and necessity of the issues you address in your report.

Include your contact information after the conclusion. Create a final section titled "Recommendations" to list any other people who support the thrust of your report. The recommendations can include co-workers, colleagues and those in upper management. Include their name, contact information and a handwritten signature.