An executive summary previews the main points of an in-depth report; it is written for nontechnical people who don't have time to read the main report. The executive report contains enough information for a reader to get familiarised with what is discussed in the full report without having to read it.
Plan to create a summary each time you write a business report exceeding four pages. Write the summary after you write the main report, and make sure it is no more than one-tenth the length of the main report.
List the main points the summary will cover in the same order they appear in the main report.
Write a simple declarative sentence for each of the main points.
Add supporting or explanatory sentences as needed, avoiding unnecessary technical material and jargon.
Read the summary slowly and critically, making sure it conveys your purpose, message and key recommendations. You want readers to be able to skim the summary without missing the point of the main report.
Check for errors of style, spelling, grammar and punctuation. Ask a fellow writer to proofread and edit the document.
Ask a nontechnical person -- for example, your parents or your spouse -- to read the document. If it confuses or bores them, the summary probably will have the same effect on other nontechnical readers.
Keep your main points in mind as you write the summary. You do not need to include every point in the summary, but ensure that the major ideas are covered succinctly.