There is no penalty or interest due on a tax return with a refund. Penalties and interest are a percentage of taxes owed. If there are ZERO taxes owed then logically and mathematically ZERO amount times any percentage is ZERO dollars due. You have up to 3 years to claim a refund as the statute of limitations bars you from collecting any money. If we are talking about 2015 tax return due April 15, 2016 then you would have until April 15, 2019 to file a return or amended return to collect a refund. Interest will be paid on the amounts they held and the interest paid is better than your bank. If you file an extension then it would extend the date to October 15, 2019. New Jersey complies with the federal law. Watch out cause not all states due, until recently there was no statute of limitations for the State of California to collect money from a taxpayer!!!