(a) Amount determined on return. -- The tax commissioner may extend the time for payment of the amount of the tax shown, or required to be shown, on any return required by this article (or any periodic installment payments), for a reasonable period not to exceed six months from the date fixed for payment thereof.
(b) Amount determined as deficiency. -- Under regulations prescribed by the tax commissioner, he may extend the time for the payment of the amount determined as a deficiency of the taxes imposed by this article for a period not to exceed eighteen months from the date fixed for payment of the deficiency. In exceptional cases, a further period of time not to exceed twelve months may be granted. An extension under this subsection (b) may be granted only where it is shown to the satisfaction of the tax commissioner that payment of a deficiency upon the date fixed for the payment thereof will result in undue hardship to the taxpayer.
(c) No extension for certain deficiencies. -- No extension shall be granted under this section for any deficiency if the deficiency is due to negligence, to intentional disregard of rules and regulations, or to fraud with intent to evade tax.