Salary is the monetary consideration due to an employee at the end of the wage period for the services or work rendered by him during the period. This is one of the covenants of mutual considerations in the contract of employment be it explicit or implied.
In the first place, no differentiation in the disbursement of salary already fixed in the contract of employment with reference to the employee's status of employment as probationer or confirmed.
Second, even among the probationers, the employer can not have any discrimination in regard to salary with reference to service rendered during notice period.
Third, if an employee fails to fulfill the notice condition, you can adjust the notice period salary proportionately against his salary payable. You cannot reduce it to his basic salary.
Fourth, when there is a provision for mutual discussion regarding notice condition, you can persuade the employee to serve the entire notice period. Finding a suitable substitute within the full notice period is the botheration of the employer. When it is not possible, such a situation cannot be a proper reason for compelling the outgoing employee to serve more than the notice period or for that reason paying the salary at a reduced rate. Certainly, it is an illegal deduction.