For the purpose of ascertaining the amount of tax payable under this act, it shall be the duty of every association liable to pay tax under this act, on or before the fifteenth day of April of each year, to transmit to the department upon a form prescribed, prepared and furnished by the department, a report under oath or affirmation, of its president, vice-president or other principal officer and of its treasurer or assistant treasurer of net income taxable under the provisions of this act.

The failure of any association liable to pay tax under this act to procure or receive any report form shall not excuse it from making a report. Every association, upon the date its report is required herein to be made, shall pay to the department the tax due to the Commonwealth by it for the preceding year.

The amount of the tax imposed under this act not paid on or before the time, as above provided, shall bear interest at the rate of six per centum (6%) per annum from the date it is due and payable until paid: Provided, however, That any association may pay the full amount of such tax, or any part thereof, together with interest due to the date of payment, without prejudice to its right to present and prosecute a petition for resettlement, a petition for review, or an appeal to court. If it be thereafter determined that such taxes were overpaid the department shall enter a credit to the account of such association which may be used by it in the manner prescribed by law.

If the officers of any association shall neglect or refuse to make any report, as herein required, or shall knowingly make any false report, an additional ten per centum (10%) of the amount of the tax shall be added by the department to the tax determined to be due.

If any association closes its fiscal year not upon the thirty-first day of December, but upon some other date, such association shall certify such fact to the Department of Revenue and shall make the report herein required on or before the fifteenth day of the fourth month after the close of its fiscal year.