When you resign your job, it needs to be done properly and done in a good way so as not to inconvenience your boss, your previous firm AND, most importantly from your vantage point, to keep this person is a reference and not have them sabotage you in the future.
The way to do it is (1) get your offer letter in writing from the new employer. Without that, you don't have legal protection.
2. Meet with your boss and try to do it on Friday, or Friday afternoon. As soon as you said the magic words, "Can I see you for a minute," they know what is coming. That's the proper way to do it. You do it in person; you don't just send them an email. Make time to meet with them on Friday afternoon. If they're not in, for whatever the reason is, do it Monday morning 1st thing . So when they come in. having been out that Friday, Monday morning 1st thing, "Can I see you for a moment?"
3. Give 2 weeks notice. No matter what they say, no amount of time is going to be good from their vantage point. Your new employer needs you and wants you within 2 weeks. Give 2 weeks notice. When they start begging you, "Can you make it 6 weeks? " Or a month. Or 3 weeks. "My new firm needs me there. If you need me to do some after-hours work or take some calls after hours, I would be happy to do that. However, I need to give 2 weeks notice."
4. A simple resignation letter. It shouldn't go into all sorts of onerous things. It might simply be, "I have decided to resign my position with (put in the name of the company) and accept the new position. My last date of employment will be such and such. ." You are being very clear when you're going into the resignation, you are going to hand in a letter, so is there, handed to them. "Thank you for the opportunity to work for you. I have learned a lot here, but I have decided to accept another position." That's it. Sweet and simple. "Very truly yours."
5. When you are asked why you are changing jobs, saying absolutely nothing that is critical. They know the problems that you have had, but instead, point to the opportunity going forward.
"I have been very happy here. I have learned a lot. " If you haven't been happy, it is been obvious to them. "I have an opportunity here to leverage my experience and learn even more. Just it would be a great choice.
6. If they decide to extend the counteroffer to you, in many situations, counteroffers are very tempting. After all, suddenly they are going to go, "Hey! I know you are worth $125,000 today, this afternoon, you are now worth $145,000! Isn't that great!" Accepting a counteroffer doesn't do anything to remedy the other things that were problematic for you with the job. If anything, it suggests they think they can buy you. Although they will promise to change those things, eventually, what starts to happen is they will backslide into old behavior patterns.
Please don't misunderstand this analogy. I think it is a valid one. I'm not trying to be hurtful to those who experience this. In the case for spouses been abused or partner has been abused by a dominant person in the house, there is always that promise. "I won't do that again. I promise." Unfortunately, in way too many situations, the promises just hot air. The old behavior returns.
The same thing exists when they promised to changing how they manage you, what your work is going to be like; maybe for a little while. It will change. But, invariably, there is a backslide that occurs.
It's very very rare that I encourage people to take a counteroffer. So I will say it again – – don't really consider a counteroffer unless you are shocked by something that they do other than the money.