765 ILCS 605/6
Upon compliance with the provisions of Sections 3, 4, and 5 and upon recording of the declaration and plat the property shall become subject to the provisions of this Act, and all units shall thereupon be capable of ownership in fee simple or any lesser estate, and may thereafter be conveyed, leased, mortgaged or otherwise dealt with in the same manner as other real property, but subject, however, to the limitations imposed by this Act.
Each unit owner shall be entitled to the percentage of ownership in the common elements appertaining to such unit as computed and set forth in the declaration pursuant to subsection (e) of Section 4 hereof, and ownership of such unit and of the owner's corresponding percentage of ownership in the common elements shall not be separated, except as provided in this Act, nor, except by the recording of an amended declaration and amended plat approved in writing by all unit owners, shall any unit, by deed, plat, judgment of a court or otherwise, be subdivided or in any other manner separated into tracts or parcels different from the whole unit as shown on the plat, except as provided in this Act.
The condominium instruments may contain provisions in accordance with this Act providing for the reallocation and adjustment of the percentage of ownership in the common elements appertaining to a unit or units in circumstances relating to the following transactions: an add-on condominium; condemnation; damage or destruction of all or a portion of the property; and the subdivision or combination of units. Interests in the common elements shall be re-allocated, and the transaction shall be deemed effective at the time of the recording of an amended plat depicting same pursuant to Section 5 of this Act. Simultaneously with the recording of the amended plat, the developer in the case of an add-on condominium, or the President of the board of managers or other officer in other instances authorized in this Act shall execute and record an amendment to the declaration setting forth all pertinent aspects of the transaction including the reallocation or adjustment of the common interest. The amendment shall contain legal descriptions sufficient to indicate the location of any property involved in the transaction.
765 ILCS 605/6