Dear [name of boss],
I’d like to request for a sabbatical. This has become traditional practice in the corporate world.
I believe that taking this leave will furnish me with tax benefits and will allow me to revitalize myself. Hence, I will come back devoted to my work.
I’dlike to take a sabbatical so that I could: [provide reasons, e.g. write a novel, study].
I hope that you can accommodate me with this request. I take great pleasure in working for your company. I hope I can remain as your employee in the long term.