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. Add contact details, company name, and date. Please accept this letter as my formal resignation. Today will be my last day of work. The series kicks off on Jan. 24 with Scott LaDeur, Ph.D., a political science professor at North Central.