Dear Sovan,
Reducing wages/salary as part of punishment for non-performance and deducting Provident Fund contribution (as well as ESI contribution or welfare fund contribution) from the salary are two different things. The former shall be done after following a procedure, such as performance appraisal followed by the issuance of letters requiring the employee to improve, issuance of a show-cause notice to explain why action of reduction to a lower scale of pay should not be initiated, conducting an enquiry if required, etc., are carried out.
On the other hand, deduction of statutory contributions from salary, like PF, ESI, etc., is permitted even if it is not mentioned in the appointment order. Not only EPF or ESI, but any deduction permitted by Section 7 of the Payment of Wages Act is legal. Yes, certainly, any amount to be contributed by the employer towards these social security schemes should not be deducted from the salary.
Regards,
Madhu.T.K