How to write a resignation letter that's effective immediately? In the first sentence, clearly state your intention to resign and that your resignation is effective immediately.Learn how to write an immediate resignation letter with our comprehensive guide, including tips, examples, and a customizable template. Learn how to write a short notice resignation letter with this stepbystep guide, template and examples of formal resignation. State your position on the day of resignation: Always mention the position you held in the office on your last working day.