New Jersey Statutes Title 54. Taxation 54 § 49-6

a. After a return or report is filed under the provisions of any State tax law, the director shall cause the same to be examined and may make such further audit or investigation as he may deem necessary, and if therefrom he shall determine that there is a deficiency with respect to the payment of any tax due under such law, he shall assess the additional taxes, penalties, if any, pursuant to any State tax law or pursuant to this subtitle, and interest at the rate of three percentage points above the prime rate due the State from such taxpayer assessed for each month or fraction thereof, compounded annually at the end of each year, from the date the tax was originally due until the date of actual payment, give notice of such assessment to the taxpayer, and make demand upon him for payment.

b. No assessment of additional tax shall be made after the expiration of more than four years from the date of the filing of a return;  provided, that in the case of a false or fraudulent return with intent to evade tax, or failure to file a return, the tax may be assessed at any time.  If a shorter time for the assessment of additional tax is fixed by the law imposing the tax, the shorter time shall govern.  If, before the expiration of the period prescribed herein for the assessment of additional tax, a taxpayer consents in writing that such period may be extended, the amount of such additional tax due may be determined at any time within such extended period.  The period so extended may be further extended by subsequent consents in writing made before the expiration of the extended period.  For purposes of this subsection, a return filed before the last day prescribed by law or by regulations promulgated pursuant to law for the filing thereof, shall be considered as filed on such last day.