Eight of the 20 Premier League clubs are being urged to ensure they pay the real living wage to all their staff.
The other 12 say they are either accredited Living Wage Foundation employers, or pay the real living wage to all staff, including subcontractors.
Staff working in a London borough will earn £11.95 an hour, or £10.90 outside of that, after an increase on Thursday.
But eight do not pay that rate to all permanent and casual matchday staff, or could not confirm if they do.
Premier League clubs spent a record £1.9bn on players over the summer.