From an examination of 74 schools, the commission found the average salary of new appointments has dropped for the past three years. The average new appointment salary scale has fallen from just more than seven to just more than five.
The commission offers no reason for the fall but teaching unions claimed financial pressure is forcing schools to recruit less experienced staff.
The study also found the number of deputy heads had been cut and more cheaper classroom assistants had been appointed. Hours per pupil spent on administration increased by 5.8% but fell in local education authority schools by 5.5%.