(a) Payments of operating subsidy under the formula. HUD shall make monthly payments equal to 1⁄12 of a PHA's total annual operating subsidy under the formula by electronic funds transfers through HUD's automated disbursement system. HUD shall establish thresholds that permit PHAs to request monthly installments. Requests by PHAs that exceed these thresholds will be subject to HUD review. HUD approvals of requests that exceed these thresholds are limited to PHAs that have an unanticipated and immediate need for disbursement.

(b) Payments procedure. In the event that the amount of operating subsidy has not been determined by HUD as of the beginning of the funding period, operating subsidy shall be provided monthly, quarterly, or annually based on the amount of the PHA's previous year's formula or another amount that HUD may determine to be appropriate.

(c) Availability of funds. In the event that insufficient funds are available, HUD shall have discretion to revise, on a pro rata basis, the amounts of operating subsidy to be paid to PHAs.