If the establishment is covered under PF once, then irrespective of the salary, they are to be covered under PF at least subject to the ceiling limit. If in a new establishment, the basic salary of all the employees is above Rs. 15K, then you can think that you need not cover since no one falls within the definition. Otherwise, it is necessary to get an Employer Code Number for an establishment and cover the employees under the Scheme.
Regards,