In the USA, there is no legal requirement for employees to give a minimum notice period when resigning. The existence of a notice period is a matter of agreement that should be set out in the employment agreement between employer and employee.
If adding a notice clause to an employment contract, standard practice in the USA is to require employees to give at least 2 weeks’ notice when resigning. The notice period may differ for specialist employees or those employed in senior roles, in these cases 4 weeks’ notice is usually required.
Giving notice isn’t a legal requirement in the USA. There are no laws requiring employers or employees to give notice but both parties must abide by the terms of the employment agreement.
Where a party has breached the employment agreement by failing to give sufficient notice, it may trigger a lawsuit, where the claimant seeks financial damages.
Yes, it’s possible to shorten the notice period in the USA. This would require both parties to agree on a new employment termination date.