A person joins an Organization based on his knowledge & Skills, assessed during the interviews, vis-à-vis his academics. If you feel the person to be recruited is good in academics or has potential, but due to lack of experience, cannot take up the role assigned for, then you recruit him/her as a Trainee.
A Trainee appointment letter / contract is to be issued at the time of joining which clearly indicates the level, remuneration and expectations.
After successful completion of Training Period, the Trainee is appointed as a regular employee on probation, and accordingly a separate appointment letter is issued to him with the JD & KRA of a regular employee.
Please note that except for Trainee under Apprentice Act, all for statutory benefits of PF / Bonus / Gratuity, the date of joining shall remain in records the one when the employee was recruited as Trainee, and not when he was appointed as a regular employee.
Hope this clarifies a bit, you query regarding Trainees and the issuance of appointment letter.
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Regards
Ketan Shetty