The occupation tax levied pursuant to §23-1 shall be due and payable on the fifteenth day of each month for the gross receipts of the month preceding such date, and each and every payment shall be made on the fifteenth day of each month, and all deferred payments shall draw interest at the rate of one percent per month, and after payment has been in default six months, a penalty of five percent shall be added thereto in addition to such interest charge which shall be paid by any person subject to this occupation tax.