On or before April fifteenth following the close of each calendar year, in the case of persons reporting on the basis of a calendar year, and on or before the fifteenth day of the fourth month following the close of a fiscal year, in the case of persons reporting on the basis of a fiscal year, each person who earns, receives, accrues or has credited to his account any dividends, interest income or gains from the sale or exchange of capital assets as defined in § 12-505, shall duly execute and file a tax return with the commissioner, in such form and containing such information as he may prescribe, which return shall truly and accurately set forth the amount received and the taxpayer‘s liability under this chapter; and the full amount of the tax shall be due and payable to the commissioner on or before the date prescribed herein for the filing of the return.