How to write a resignation letter that's effective immediately? Subject: Immediate resignation due to family emergency.It's best to tell your boss that you're moving on to the next step in your career "facetoface or over video call," with at least two weeks' notice. Dear Mr. Clark, I am writing to inform you that I am resigning from my position at Innovate Tech Labs, effective immediately. Your resignation letter should be to the point, concise, and clear.