The day rate is the amount actually paid to the teacher before deductions for a day's work.
For a supply teacher being paid through the payroll, the daily cost is the total cost to the school including employers' costs. The employers NI contribution (which has been estimated), employers pension contribution and Airsupply fee has been added to the teacher's day rate.
For self employed teachers, the daily cost will be the day rate plus the Airsupply fee.
The Airsupply fee will be paid by invoice not through the payroll.