The purpose of local subsidies, like that of State subsidies, is to assist in achieving and maintaining the low rent character of a project. All or part of a local subsidy may be in the form of tax exemption (see § 1648-2.2, below) but the aggregate local subsidy for a given year, whether in the form of tax exemption or cash, or both, must at least equal the State subsidy, as where the value of tax exemption is in excess of the amount required to match the State subsidy or where the operating deficit is in excess of the maximum State subsidy, or where the municipality is bound by special provisions of the loan and subsidy contract, to pay a minimum annual cash subsidy.