Rule 3220. Offer to liquidate damages conditionally. At any time not
later than ten days before trial, any party against whom a cause of
action based upon contract, express or implied, is asserted may serve
upon the claimant a written offer to allow judgment to be taken against
him for a sum therein specified, with costs then accrued, if the party
against whom the claim is asserted fails in his defense. If within ten
days thereafter the claimant serves a written notice that he accepts the
offer, and damages are awarded to him on the trial, they shall be
assessed in the sum specified in the offer. If the offer is not so
accepted and the claimant fails to obtain a more favorable judgment, he
shall pay the expenses necessarily incurred by the party against whom
the claim is asserted, for trying the issue of damages from the time of
the offer. The expenses shall be ascertained by the judge or referee
before whom the case is tried. An offer under this rule shall not be
made known to the jury.