In the body of the letter, state your intended retirement date (your last day) and your thoughts on a transition plan. How to write a retirement letter to an employer?What should you say in a retirement letter? Include the position title and the last day you intend to work. Save time writing your resignation or retirement letter with these customizable, stress-free templates. Save time writing your resignation or retirement letter with these customizable, stress-free templates. Try to obtain reference letters before you submit your resignation. In the opening paragraph, make it clear that you are retiring. A retirement letter is a letter of intent to retire. It's a resignation letter informing your employer of your intentions to leave the company.