In the opening paragraph, make it clear that you are retiring. Want to know how to write a retirement letter of resignation?Get the insights you need and free retirement letter template to help guide the way. Time frame: Clearly state your last planned day of employment. A retirement letter is an official notice stating an individual's resignation from their position and requesting any retirement benefits. Check out our retirement resignation letter selection for the very best in unique or custom, handmade pieces from our templates shops.