215 ILCS 5/357.22
"CANCELLATION: The company may cancel this policy at any time by written notice delivered to the insured, or mailed to his last address as shown by the records of the company, stating when, not less than 30 days thereafter, such cancellation shall be effective; and after the policy has been continued beyond its original term the insured may cancel this policy at any time by written notice delivered or mailed to the company, effective upon receipt or on such later date as may be specified in such notice. In the event of cancellation, the company will return promptly the unearned portion of any premium paid. If the insured cancels, the earned premium shall be computed by the use of the short-rate table last filed with the state official having supervision of insurance in the state where the insured resided when the policy was issued. If the company cancels, the earned premium shall be computed pro-rata. Cancellation shall be without prejudice to any claim originating prior to the effective date of cancellation." (Notice to the policy holder of the cancellable nature of his policy shall be set forth on the face of the policy.)
215 ILCS 5/357.22