Signed somewhere else last week and now I have to tell a manager who genuinely went out of his way for me. I keep rewriting the message and it comes out either cold or weirdly apologetic. Do you tell your manager before HR? How much do you explain when they ask why, and do you say where you're going? Two years here and I'd like to leave it clean rather than just survive it.
One thing I'd add: decide what you'll say to a counteroffer before you walk in, because it arrives fast and it's flattering. I hadn't, and I lost a week wobbling over a number that was never the reason I was leaving. And don't check out during notice — the handover doc you write in those last two weeks is genuinely what people remember you by.
Manager first, always, and before HR has the paperwork. Keep it short: you've accepted something else, your last day is X, and you want to hand over properly. You don't owe anyone the reason or the company name, and "it lines up better with where I want to go next" politely ends the follow-up. The ones who went out of their way for you are mostly just going to be glad for you.
