Simply replace the unfilled areas such as "" and "[date]" with your information.
Dear [name of boss],
I'd like to request a sabbatical. As you know, this request is becoming more and more common in the corporate world.
Taking a formal sabbatical provides me with certain tax advantages, and guarantees you that I'll return refreshed and rededicated to my work.
I'd like to take a sabbatical for the following reasons: [list reasons, i.e. to go on an extended trip, write a novel, spend more time with the family].
I hope you'll give my request serious consideration. I love working here, and I hope to stay in your employment for a long time.