I don't do NJ, but a quick look at the rules state Homeowners and tenants who pay property taxes on a primary residence (main home) in New Jersey, either directly or through rent, may qualify for either a deduction or a refundable credit when filing an Income Tax return.

I don't know for sure but I would think if you use the 18% it would be a deduction and not a credit, but you need to look up the rules yourself.