All taxes paid pursuant to this chapter shall be deemed allowable and reimbursable costs for federal Medicaid reimbursement purposes. The department shall make appropriate adjustments to the methods and standards for reimbursing nursing facilities under section 346-14 by a Medicaid state plan amendment which shall become effective on federal approval. In the case of any program involving federal Medicaid participation, the adjustment shall take effect no earlier than the effective date of any federally-approved Medicaid state plan amendment containing any such adjustment.