Whenever salary or other matters requiring appropriation of money by any municipal employer are to be included as matter of negotiation or collective bargaining conducted under the provisions of this chapter, the negotiating or bargaining agent must first serve written notice of request for negotiating or collective bargaining on the municipal employer at least one hundred twenty (120) days before the last day on which money can be appropriated by the municipal employer to cover the first year of the contract period which is the subject of the negotiating or bargaining procedure.
R.I. Gen. Laws § 28-9.4-9