R.I. Gen. Laws § 44-14-6: Filing of annual return.

(a) Every taxpayer shall file a return with the tax administrator:

(1) In case the taxable year of the taxpayer is the calendar year, on or before March 15 in the year following the close of the taxable year; and

(2) In case the taxable year of the taxpayer is a fiscal year, on or before the fifteenth (15th) day of the third (3rd) month following the close of the fiscal year.

(b) For tax years beginning after December 31, 2015, a return, in the form and containing the information that the tax administrator may prescribe, shall be filed with the tax administrator by the taxpayer on or before the date a federal return is due to be filed, without regard to extension.