Employees engaged through a contractor do not have an employee-employer relationship with the principal employer. Therefore, they cannot claim direct employment with the principal employer, even if they have worked for the entire year with them. However, if the principal employer has behaved in a manner that indicates the existence of the aforementioned relationship, then the contractor's employees can request direct employment status. For instance, if the principal employer has participated in a conciliation proceeding where the wages and other conditions of service of the contractor's employees were discussed and finalized, it should be interpreted as the principal employer establishing an employer-employee relationship with these employees. This situation may result in a scenario where the principal employer cannot deny permanent employment to the contractor's employees.
If by contractual employment you mean employment for a fixed term or fixed-term contract (FTC), then the employee will be on your payroll only. To prevent them from claiming permanent employment status, you will need to limit their working days to fewer than 240 days in a year.
Regards,
Madhu.T.K