R.I. Gen. Laws § 44-11.1-3: Filing of tax returns — Due date.

A tax return in the form and containing the information that the tax administrator may prescribe shall be filed with the tax administrator by the political organization:

(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.