Every hospital shall on or before the fifteenth day of April in the taxable period make a return to the commissioner. The commissioner shall adopt rules, pursuant to RSA 541-A, relative to the form of such return and the data which it must contain for the correct computation of net patient services revenue and the tax assessed upon such amount. All returns shall be signed by the taxpayer or by its authorized representative, subject to the pains and penalties of perjury. If such return shows an overpayment of the tax due, the commissioner shall refund or credit the overpayment to the hospital in accordance with N.H. Rev. Stat. § 21-J:28-a. Every hospital shall on or before January 15 in the taxable period make a nonbinding estimate of its projected tax payment.