§11-13V-6. Time for filing annual returns and other documents.
On or before the expiration of one month after the end of the
taxable year, every taxpayer subject to a tax imposed by this
article shall make and file an annual return for the entire taxable
year showing all information the Tax Commissioner requires and
computing the amount of taxes due under this article for the
taxable year. Returns made on the basis of a calendar year shall
be filed on or before the thirty-first day of January following the
close of the calendar year. Returns made on the basis of a fiscal
year shall be filed on or before the last day of the first month
following the close of the fiscal year.