Question to Ask the Workplace Doctors about applying for another job:
How do I write a letter informing my boss that I’m applying for another job within the same company?
Your “how” question also is a “why” question. Why write a letter? The answer to that probably is that you think that it would be good that you inform your boss you are applying for another job rather than that she/he learn that from some other source. You don’t want her/him learning you are applying to be a surprise. Because???