(1) Each June and at such other times as may be necessary, the board will establish, review, and revise the adjusted gross annual income limits for lower income persons and families deemed to require assistance under board programs. In establishing these limits, the board will consider:

(a) the amount expressed as a percentage of total personal and family income, assets, and other financial resources that can be reasonably devoted to housing needs as defined in information provided by federal housing assistance programs and the private enterprise system;

(b) the size of families and allowable exemptions and deductions to be used in determining adjusted gross annual income as defined in federal housing assistance programs and federal and state tax allowances;

(c) the needs of particular lower income persons and families, such as the elderly and physically and mentally handicapped;

(d) the eligibility standards of current federal housing assistance programs;

(e) the costs and availability of housing in rural and urban areas provided in information supplied by lending institutions, realtors, homebuilders, governmental agencies and public interest groups; and

(f) the ability of persons and families to pay the cost of available housing or of new housing provided by private enterprise, in terms of the percentage of adjusted gross annual income required for that purpose.

(2) Adjusted gross annual income limits specified in federal assistance programs utilized by the board in any of its programs will be observed where applicable.

(3) In general, the costs of housing for the purpose of establishing adjusted gross annual income limits will be deemed to be an amount necessary to pay for:

(a) in the case of homeowners, the annual costs of amortization of the permanent loan mortgage, together with the annual costs of real estate taxes, including any assessments, fire and extended property insurance coverage, and utilities, except for telephone; or

(b) in the case of tenants, the annual amount of rental charges plus the annual costs of utilities, except for telephone.

(4) The board may waive income limits in its mortgage purchase program, to enable the board to purchase existing mortgage loans without regard for its current income limits.