65 ILCS 5/9-3-41
Whenever any assessment has been levied against any real estate, the assessment or installments thereof shall become delinquent the first day of July next after the due date thereof and bear interest after delinquency at the rate as in this Division 3 provided until paid, or until such real estate is sold for the payment thereof, as in this Division 3 provided. The assessment after delinquency shall continue to be collected by the authorized collector of any such municipality. Such municipality shall institute proceedings to foreclose and sell property for the payment of any assessment, or installment thereof, remaining delinquent 6 months after delinquency date. Any holder of any bond or of any interest coupon is entitled to summary relief by mandamus or injunction to enforce the provisions hereof.
65 ILCS 5/9-3-41