How to write a resignation letter that's effective immediately? Learn how to craft a professional resignation letter without notice with our guide.An employee absent for two or more scheduled work days without notice, permission or without good reason will be considered as having resigned. a. Learn how to write an immediate resignation letter with our comprehensive guide, including tips, examples, and a customizable template. Your letter of resignation should be short and professional. If someone gives a resignation letter without giving the required one month's notice, what can his employer do against him (like filing a complaint)?