Defendant employer did not pay its arbitration fees within 30 days after their due date.  Under CCP 1287.98, plaintiff therefore had and exercised the right to withdraw his claim from arbitration and pursue it in court.  The arbitrator or arbitration administrator had no power to avoid the effect of defendant’s nonpayment by extending the due date after defendant’s default.  Also, the court, not the arbitrator, determines whether withdrawal of the claim from arbitration is proper under the statute, since the arbitrator is self-interested in that decision.