I would not recommend giving notice ahead of an involuntary termination in the case of either underperformance or misconduct. Such notice is usually reserved for a layoff. More importantly, it could expose your company to additional risk:
- The to-be-terminated employee may misuse company property, steal proprietary information, or harm the company in other ways.
- This notice would set a precedent that other employees might expect for themselves, and if they don’t receive the same notice, they may claim that you’re discriminating against them.
- The work the employee does during this time may be subpar or disruptive. On the other hand, their performance may improve, in which case you may be tempted to renege on the termination. This would muddy expectations with regard to the original termination notice.
Given these risks, I recommend that terminations take effect immediately after or the same day the employee receives notice.