Establish Your Objective
The objective of an acceptance letter is to say "yes" to an invitation or a job offer. It notifies the reader of this decision and affirms the writer's commitment.
Your acceptance should be conveyed in the first sentence, especially when you are accepting a job offer. Include a simple "thank you" as you begin the letter. Courtesy never goes out of style and your reader will appreciate your attention in that regard.
In the sample acceptance letter the writer accepts a job offer and asks for confirmation regarding a previously determined start date.