The company can change its policies at any time. The basic salary has to be between 30% to 60%; hence, a 31% fixation is supported.
Secondly, there is no legal provision that curtails the right of an employer to reduce the salary given to their employees, as long as it is in accordance with the minimum wages.
Thirdly, the process of converting temporary employees into permanent ones based on "performance" is always an important criterion. Temporary employees are not absolute employees of the company like permanent employees. When temporary employees are made permanent, it is almost like being freshly recruited, with the only significant difference being that the employer and employee know each other well.
ESI or PF cannot be claimed when a stipend is paid. Technically, it is not a salary or wage but a supportive pay to encourage students, trainees, or interns.
It is not the basic pay of 40% and 50%, but HRA (House Rent Allowances). In metros, 50% of the basic salary is paid to meet the cost of living, while in other places, it is 40%.
No employer can avoid paying the PF/ESI; it is mandatory and stands at 12% of the basic pay of the employees.