In NJ is there a law stating me to give my tenants a grace period?

Yes and no. If the lease calls for payment on the first the first is the due date. They do have a grace period to the fifth, not the eighth.

If the rent is due on the first, , a grace period until the 5th day of the month is common in leases. Be advised that a grace period does not mean the rent is not due until the 5th day. That is simply the time the tenant has to pay the rent to avoid assessment of a late charge.

N.J.S.A. 2A:42-6.1 Grace period for payment of rent A person to whom rent is due and payable on the first of the month upon a lease or other agreement shall allow a period of five business days grace in which the rent due shall be paid. No delinquency or other late charge shall be made which includes the grace period of five business days. As used in this section, ““business day”” means any day other than a Saturday, Sunday or State or federal holiday. This section has only limited applicability. A common misconception is that the five day grace period applies to all tenancies, but the five day grace period provided for at N.J.S.A. 2A:42-6.1 for the payment of rent is restricted by N.J.S.A. 2A:42-6.3 to tenants receiving certain pensions, disability benefits from Social Security, or certain specified State benefits. : N.J.S.A. 2A:42-61.3 Applicability of act The provisions of this act shall only be applicable to premises rented or leased by senior citizens receiving Social Security Old Age Pensions, Railroad Retirement Pensions or other governmental pensions in lieu of Social Security Old Age Pensions, and by recipients of Social Security Disability Benefits, Supplemental Security Income or benefits under Work First New Jersey.