(a) At any time more than 10 days before the trial begins, either the party making a claim or the party defending against a claim may serve upon the adverse party an offer to allow judgment to be entered in complete satisfaction of the claim for the money or property or to the effect specified in the 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, and the clerk shall enter judgment. An offer not accepted within 10 days is considered withdrawn, and evidence of that offer is not admissible except in a proceeding to determine the form of judgment after verdict. If the judgment finally entered on the claim as to which an offer has been made under this section is at least five percent less favorable to the offeree than the offer, or if there are multiple defendants at least 10 percent less favorable to the offeree than the offer, the offeree, whether the party making the claim or defending against the claim, shall pay all costs as allowed under the Alaska Rules of Civil Procedure and shall pay reasonable actual attorney fees incurred by the offeror from the date the offer was made, as follows:

1. (1) if the offer was served no later than 60 days after both parties made the disclosures required by the Alaska Rules of Civil Procedure, the offeree shall pay 75 percent of the offeror's reasonable actual attorney fees;
2. (2) if the offer was served more than 60 days after both parties made the disclosures required by the Alaska Rules of Civil Procedure but more than 90 days before the trial began, the offeree shall pay 50 percent of the offeror's reasonable actual attorney fees;
3. (3) if the offer was served 90 days or less but more than 10 days before the trial began, the offeree shall pay 30 percent of the offeror's reasonable actual attorney fees.