N.Y. Comp. Codes R. & Regs. tit. 11 § 65-3.9 : INSURANCE — Policy and Certificate Provisions — Property and Casualty Insurance — Regulations Implementing The Comprehensive Motor Vehicle Insurance Reparations Act —3 - Claims For Personal Injury Protection Benefits —3.9 - Interest on overdue payments

(a) All overdue mandatory and additional personal injury protection benefits due an applicant or assignee shall bear interest at a rate of two percent per month, calculated on a pro-rata basis using a 30-day month. When payment is made on an overdue claim, any interest calculated to be due in an amount exceeding $5 shall be paid to the applicant or the applicant's assignee without demand therefor.
(b) The insurer shall not suggest or require, as a condition to settlement of a claim, that the interest due be waived.
(c) If an applicant does not request arbitration or institute a lawsuit within 30 days after the receipt of a denial of claim form or payment of benefits calculated pursuant to Department of Financial Services regulations, interest shall not accumulate on the disputed claim or element of claim until such action is taken. If any applicant is a member of a class in a class action brought for payment of benefits, but is not a named party, interest shall not accumulate on the disputed claim or element of claim until a class that includes such applicant is certified by court order, or such benefits are authorized in that action by Appellate Court decision, whichever is earlier.
(d) If an applicant has submitted a dispute to arbitration or the courts, interest shall accumulate, unless the applicant unreasonably delays the arbitration or court proceeding.
(e) The insurer shall separately identify any interest payment on an overdue claim from benefit payments. This may be done by issuing separate drafts for each amount or by an accompanying statement that clearly and separately identifies the components of the draft.
(f) An insurer may not include in its rate making calculations any interest paid on an overdue claim.

N.Y. Comp. Codes R. & Regs. Tit. 11 § 65-3.9