N.J. Stat. Ann. § 30:4D-17.4

If an applicant is determined to be eligible under P.L. 1968, c. 413 (C. 30:4D-1 et seq.) retroactively and the provider bills the applicant directly for the services and benefits rendered during the retroactive period, the provider shall, upon notification of the applicant's retroactive eligibility, submit claims for reimbursement for covered services or benefits rendered during the retroactive period. Upon certification that the applicant is so eligible, the provider shall reimburse the applicant or other person who has made prior payment to the provider.