Rule 68 - Offer of judgment and disclaimer(a) Offer of judgment. - At any time more than 10 days before the trial begins, a party defending against a claim may serve upon the adverse party an offer to allow judgment to be taken against him for the money or property or to the effect specified in his offer, with costs then accrued. If within 10 days after the service of the offer the adverse party serves written notice that the offer is accepted, either party may then file the offer and notice of acceptance together with proof of service thereof and thereupon the clerk shall enter judgment. An offer not accepted within 10 days after its service shall be deemed withdrawn and evidence of the offer is not admissible except in a proceeding to determine costs. If the judgment finally obtained by the offeree is not more favorable than the offer, the offeree must pay the costs incurred after the making of the offer. The fact that an offer is made but not accepted does not preclude a subsequent offer.(b) Conditional offer of judgment for damages. - A party defending against a claim arising in contract or quasi contract may, with his responsive pleading, serve upon the claimant an offer in writing that if he fails in his defense, the damages shall be assessed at a specified sum; and if the claimant signifies his acceptance thereof in writing within 20 days of the service of such offer, and on the trial prevails, his damages shall be assessed accordingly. If the claimant does not accept the offer, he must prove his damages as if the offer had not been made. If the damages assessed in the claimant's favor do not exceed the sum stated in the offer, the party defending shall recover the costs in respect to the question of damages.