An employee who has neglected his/her duties based on the employment relationship or who has committed a breach thereof, should not be given notice before been given a warning and there through an opportunity to amend their conduct. However, if the conduct has been serious or crude, there is no obligation to give a warning. In these situations the employer can cancel the employment relationship to end immediately.
Warning should be given within reasonable time after the ground has come to the employer's knowledge. A reasonable period cannot be longer than a month, but it is always recommended that the warning is given as soon as possible.
The warning can be verbal or in writing. It shall be given in a provable manner, e.g. so that the employee must sign for it or (impartial) witnesses are present and can testify that the warning was given.
The warning must be clear and justified, so that the employee understands that his/her employment relationship may be terminated if he/she does not change his/her behavior. Employees must also be given a genuine opportunity and reasonable time after the warning to amend his/her conduct and behavior.