There’s a fascinating discussion over at FatWallet started by a software engineer who is planning to switch careers to project management at another company. While his situation poses several questions related to quitting one’s job, the one he really asks is how much notice he should give his current employer. He knows he’ll be starting the new job in four months; and while his present manager is looking for a new contract for him, he’s wondering if he should tell his manager now that he’s leaving in four months or wait for fear of early termination.

This guy has a very good reason to question when he should alert his employer of his impending departure. Most workers, unless they have a contract to the contrary, are employeed at-will–you can quit your job anytime, but you can also be fired at any time for any legal reason. Firing someone who is planning to quit a few months down the road is perfectly legitimate, and it probably happens from time to time.

For me, determining the amount of notice to give is a matter of following two simple guidelines.

1. Be honest with yourself first. If you realize you can be somewhat easily replaced with a co-worker or new hire, give the industry standard notice of two weeks. Nobody will blame you… but probably because they won’t miss you that much.
2. If you’re a critical employee with uncommon skills or whose sudden absense would cause a major upset in your workplace, give additional notice. Give as much notice as you can, in fact. It’s important to keep the bridges intact with a workplace that deems you to be a major asset, and giving extra notice will help you achieve that. Assuming you are as important as you think you are, you shouldn’t have to worry about early termination since your employer will probably want to squeeze as much work out of you as possible before you go.

You should also find out how much notice people you work alongside give when they leave for another job. If you find that most are giving a month notice and not being terminated early, you can probably do the same safely.