At least in the US, the gym has to be exclusive to employees and their families to qualify for a tax benefit.
> You can exclude the value of an employee's use of an on-premises gym or other athletic facility you operate from an employee's wages if substantially all use of the facility during the calendar year is by your employees, their spouses, and their dependent children. For this purpose, an employee's dependent child is a child or stepchild who is the employee's dependent or who, if both parents are deceased, hasn't attained the age of 25. The exclusion doesn't apply to any athletic facility if access to the facility is made available to the general public through the sale of memberships, the rental of the facility, or a similar arrangement.
> You can exclude the value of an employee's use of an on-premises gym or other athletic facility you operate from an employee's wages if substantially all use of the facility during the calendar year is by your employees, their spouses, and their dependent children. For this purpose, an employee's dependent child is a child or stepchild who is the employee's dependent or who, if both parents are deceased, hasn't attained the age of 25. The exclusion doesn't apply to any athletic facility if access to the facility is made available to the general public through the sale of memberships, the rental of the facility, or a similar arrangement.
https://www.irs.gov/publications/p15b#en_US_2021_publink1000...