How to write a resignation letter that's effective immediately? Learn how to write an immediate resignation letter with our comprehensive guide, including tips, examples, and a customizable template.In the first sentence, clearly state your intention to resign and that your resignation is effective immediately. To write a good and simple resignation letter, greet your manager formally, then state your intent to resign and the date you'll officially depart. In this article, we explore what a sameday resignation letter is, why it's important to write one, how to write one and provide a template and an example.