Mont. R. Civ. P. 68

(a) Making an Offer; Judgment on an Accepted Offer. More than 14 days before the

trial begins, a party defending against a claim may serve on an opposing party an offer to

allow judgment on specified terms, with the costs then accrued. If, within 14 days after

being served, the opposing party serves written notice accepting the offer, either party may

then file the offer and notice of acceptance, plus proof of service. The clerk must then

enter judgment.

(b) Unaccepted Offer. An unaccepted offer is considered withdrawn, but it does not

preclude a later offer. Evidence of an unaccepted offer is not admissible except in a

proceeding to determine costs.

(c) Offer after Liability is Determined. When one party’s liability to another has been

determined but the extent of liability remains to be determined by further proceedings, the

party held liable may make an offer of judgment. It must be served within a reasonable

time -- but at least 14 days -- before a hearing to determine the extent of liability.

(d) Paying Costs after an Unaccepted Offer. If the judgment that the offeree finally

obtains is not more favorable than the unaccepted offer, the offeree must pay the costs

incurred after the offer was made.