If an employee tells their manager about plans to leave the company at a certain date or even hand in their resignation with a longer notice than required by the contract, there is the possibility that the company will fire the employee before the date the employee intended to leave.
This most recently came up in this question. If the employee has reasons to let the employer know earlier, they have to weigh the advantages of doing so against the risk the employer might choose to fire the employee in response.
That question led me to wonder what incentives the company would have to fire an employee they know will be leaving in six months time anyway.
If the company wanted to get rid of the employee anyway, I would not expect them to fire the employee any earlier than they otherwise would have. If they are in a jurisdiction where a termination requires a valid reason, they'll probably be happy they won't have to find one for this employee. And it's quite doubtful the resignation would constitute a valid reason for termination.
In the case of a good employee, I would expect the company to want to keep this employee for as long as they can. The longer they have this employee the more time they have to find and train a replacement.
I understand that by resigning, the employee may miss out on a bonus payout or additional training, and they are likely not going to get the most exciting work assignments. But are they actually likely to get fired?
What incentives would a company have to fire an employee once the employee has resigned or declared their intention to do so?