(1) A tax district may grant any business entity an extension of not more than six (6) months, unless a longer extension has been granted by the Internal Revenue Service or is agreed to by the tax district and the business entity, for filing its return, if the business entity, on or before the date prescribed for payment of the tax, requests the extension and pays the amount properly estimated as its tax.
(2) If the time for filing a return is extended, the business entity shall pay, as part of the tax, an amount equal to twelve percent (12%) per annum simple interest on the tax shown due on the return, but not previously paid, from the time the tax was due until the return is actually filed and the tax paid to the tax district. A fraction of a month is counted as an entire month.