N.J. Stat. Ann. § 44:7-80

No grant of medical assistance for the aged shall be made prior to the filing of an application therefor, and the making of an investigation to determine eligibility and the extent of need. No grant of medical assistance for the aged shall include any costs for services incurred prior to the date of the application, except costs for in-patient hospital services incurred within 30 days of the date of the application and subsequent to the effective date of this act.