(a) Number of units assisted. Based on the final disposition program developed in accordance with 24 CFR part 290, HUD shall determine the number of units to be assisted up to 100 percent of the units in the project.

(b) Maximum assistance. The maximum total annual housing assistance payments that may be committed under the contract shall be the total of the gross rents for all the contract units in the project.

(c) Changes in contract amounts. In order to assure that housing assistance payments will be increased on a timely basis to cover increases in contract rents, changes in family composition, or decreases in family incomes:

(1) A project account shall be established and maintained, in an amount as determined by HUD consistent with section 8(c)(6) of the Act, out of amounts by which the maximum annual contract commitment per year exceeds amounts paid under the contract for any fiscal year. This account shall be established and maintained by HUD as a specifically identified and segregated account, and payment shall be made therefrom only for the purposes of:

(i) Housing assistance payments, and

(ii) Other costs specifically authorized or approved by HUD.

(2) Whenever a HUD-approved estimate of required housing assistance payments for a fiscal year exceeds the maximum annual contract commitment, causing the amount in the project account to be less than an amount equal to 40 percent of the maximum annual contract commitment, HUD, within a reasonable period of time, shall take such additional steps authorized by Section 8(c)(6) of the Act as may be necessary to carry out this assurance, including (as provided in that section of the Act) “the reservation of annual contributions authority for the purpose of amending housing assistance contracts or the allocation of a portion of new authorizations for the purpose of amending housing assistance contracts.”