Yes in most cases. Your personal residence is the part of your property used for personal purposes. Your principal residence may include other areas on your property that are used for business.
If this is the case, you can only claim the Illinois Property Tax Credit on the part of your property used as a personal residence.
Illinois says the credit may be based on the entire property tax bill if "the tax bill included property used only for the taxpayer's personal residence, yard, garage, or other structure used for personal purposes. If the property tax bill included not only taxpayer's personal residence, but also business, rental, or farm property, that credit may be calculated only on that portion of the property tax bill that is for the personal residence."
Section 100.2180 Credit for Residential Real Property Taxes (IITA 208)