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.State your resignation. Modify the resignation statement to reflect the urgency of your notice period. Learn how to write a short notice resignation letter with this stepbystep guide, template and examples of formal resignation. Explain only what is necessary. Give a clear reason for leaving, but there is no need to over-explain. This sets the tone and leaves no room for ambiguity. An Immediate Resignation Letter is a notice that tells a manager or employer of an employee's intention to terminate their employment with immediate effect. Are you considering quitting your job?