The tax administrator may grant a reasonable extension of time for filing returns, under rules and regulations as the tax administrator shall prescribe, with the approval of the director of the department of revenue. Whenever an extension of time is granted, a taxpayer shall be required to pay as part of any tax due, interest at the annual rate prescribed by § 44-1-7 from the day when the return should have been filed as if no extension had been granted.
R.I. Gen. Laws § 44-14-7