Idaho Code § 43-2554
For the purpose of securing the payment of the principal of and interest on an issue of local improvement bonds, notes, warrants or other short-term obligations, the board may create a reserve fund for each obligation in addition to or in lieu of a guarantee fund. The reserve fund shall be separate and apart from any guarantee fund and in an amount not exceeding ten percent (10%) of the principal amount of the bonds, notes or warrants issued. The cost of a reserve fund may be included in the cost and expense of any local improvement for assessment against the property in the local improvement district to pay the cost, or any part thereof. The reserve fund may be funded from the proceeds of the bonds, notes, warrants, or other short-term obligations, from special assessment payments, or from any other money legally available therefor. Reserve fund balances in excess of ten per cent [percent] (10%) of the principal amount of the bonds outstanding shall be used to reduce the annual assessments of those participants in the respective local improvement district whose prior assessments have been paid. Whenever the reserve fund is insufficient to meet claims for payment of principal and interest against the reserve fund, the board may appropriate funds from such other legally available sources of the local improvement district as may be determined by the board.
Idaho Code § 43-2554