(735 ILCS 5/13-116) (from Ch. 110, par. 13-116)
    Sec. 13-116. Lien of mortgage, trust or vendor's lien. (a) The lien of every mortgage, trust deed in the nature of a mortgage, and vendor's lien, the due date of which is stated upon the face, or ascertainable from the written terms thereof, filed for record either before or after July 16, 1941, which has not ceased by limitation before July 16, 1941, shall cease by limitation after the expiration of 20 years from the time the last payment on such mortgage, trust deed in the nature of a mortgage, or vendor's lien became or becomes due upon its face and according to its written terms, unless the owner of such mortgage or vendor's lien, or the owner or trustee of such trust deed in the nature of a mortgage either
    (1) Before July 16, 1941, and within such 20 year period has filed or caused to be filed for record an extension agreement showing the time for which the payment of the indebtedness is extended, and the amount remaining unpaid on such indebtedness; or
    (2) After July 16, 1941, and within such 20 year period or within one year after July 21, 1947, provided the due date of the instrument was more than 19 years before July 21, 1947, files or causes to be filed for record, either (i) an affidavit executed by himself or herself or by some person on his or her behalf, stating the amount or amounts claimed to be unpaid on the indebtedness secured by such mortgage, trust deed in the nature of a mortgage, or vendor's lien; or (ii) an extension agreement executed as hereinafter provided.
    (b) The lien of every mortgage, trust deed in the nature of a mortgage, and vendor's lien, in which no due date is stated upon the face, or is ascertainable from the written terms thereof, shall cease by limitation after the expiration of 30 years from the date of the instrument creating the lien, unless the owner of such mortgage or vendor's lien, or the owner or trustee of such trust deed in the nature of a mortgage, within such 30 year period or within one year after July 21, 1947, provided the date of the instrument was more than 29 years before July 21, 1947, files or causes to be filed for record either (1) an affidavit executed by himself or herself or by some person on his or her behalf, stating the amount or amounts claimed to be unpaid on the indebtedness secured by such mortgage, trust deed in the nature of a mortgage, or vendor's lien; or (2) an extension agreement executed as hereinafter provided.
    The filing for record of an affidavit provided for by this Section, within such 20 or 30 year period or one year period, as the case may be, shall extend the lien for a period of 10 years after the date on which such lien would cease if neither an affidavit nor extension agreement were filed, and no more, and a subsequent affidavit filed within the last 10 year period of the lien, as extended, shall extend the lien for an additional 10 year period, and no more, but successive affidavits may be filed, each extending the lien 10 years.
    The filing for record of an extension agreement within such 20 or 30 year period or one year period, as the case may be, whether before or after July 16, 1941, shall extend the lien for 10 years from the date the final payment becomes due under such extension agreement, and no more, but subsequent extension agreements filed before the lien, as extended, ceases, shall extend the lien for an additional 10 year period from the date the final payment becomes due under such extension agreement, and no more. The filing of an extension agreement shall not be construed in any way to cause the lien to cease before it would cease if neither an extension agreement nor an affidavit were filed. Affidavits may be followed by extension agreements, and extension agreements may be followed by affidavits.
    An extension agreement executed after July 16, 1941, to be effective for the purpose of continuing the lien of any mortgage, trust deed in the nature of a mortgage, or vendor's lien shall show the time for which the payment of the indebtedness secured thereby is extended and the amount remaining unpaid on such indebtedness, and shall be executed and acknowledged by the owner of the mortgage, trust deed in the nature of a mortgage, or vendor's lien, or someone on his or her behalf, and by one or more persons representing himself, herself or themselves to be the then owners of the real estate. The affidavit or extension agreement shall be effective only as to the lands within the county or counties wherein such affidavit or extension agreement, or a copy thereof, is filed for record.
    When a corporation is the owner or trustee of any such mortgage, trust deed in the nature of a mortgage, or vendor's lien, the affidavit herein described shall be deemed effective for all purposes under this Section when it has been executed by any officer of such corporation, or by any person authorized by the corporation to execute such affidavit.
    The Section shall apply to mortgages, trust deeds in the nature of mortgages, and vendor's liens on both registered and unregistered lands. "Filed for record" or "the filing for record" as used in Article XIII of this Act means filing in the office of the recorder in the county in which the lands are situated, if such lands are unregistered, or in the office of the registrar of titles for such county, if such lands are registered. Nothing herein contained shall be construed to revive the lien of any such instrument which has expired by limitation before July 16, 1941.
(Source: P.A. 83-1362.)