My bill says "back taxes due". What does that mean?

According to office records, there may be past due taxes in your name or on the parcel of property in question if your taxes were not paid in full in a timely manner. Call 860-767-4340 ext. 120 or ext. 121 for updated interest charges, if applicable. Back taxes and interest must be paid in full before payment on current bill can be accepted. Any payment you send in toward your current bill will be applied to the back taxes.