14 CFR 271.7 – Subsidy payout formula
(a) Subsidy will be paid by the Department to the air carrier monthly, based on the subsidy rate established by the Department for the carrier under this part. Payments will not vary except as provided in this section.
(b) While a carrier’s subsidy rate will not vary even if actual revenues or costs differ from projections, the actual amount of each payment may vary depending on the following factors:
(1) Seasonal characteristics of the carrier’s operations at the eligible place;
(2) The actual number of flights completed, aircraft miles flown, available seat-miles flown, or variations in other operational elements upon which the subsidy rate is based; or
(3) Adjustments to the carrier’s subsidy required by § 271.8(b).
(c) Payments will continue for the duration of the rate term established under § 271.8 provided that the carrier continues to provide the required service.