Cook County, IL Historic Preservation: Historic-Cultural Monuments (2026)
Key Facts
- Investment threshold
- At least 50% of pre-rehab market value
- Incentive duration
- 12 years, renewable
- Governing section
- Cook County Code § 74-63(17)
- Approval required
- Local resolution plus preservation commission recommendation
- Administered by
- Cook County Assessor's Office
Summary
Cook County's Class L tax incentive rewards owners of landmark or contributing buildings with a reduced property assessment after substantial rehabilitation, once the property's municipality (or County Board if unincorporated) formally supports the project.
Real estate which is to be used for commercial or industrial purposes and which is designated as Class 3, Class 4, Class 5a or Class 5b pursuant to this Division; is a landmark or contributing building; and has undergone substantial rehabilitation. The substantial rehabilitation must constitute an investment by the owner of at least 50 percent of the building's full market value as determined by the Assessor in the assessment year prior to the commencement of the substantial rehabilitation.
Full Breakdown
Under Cook County Code § 74-63(17), a building already classified 3, 4, 5a or 5b qualifies for Class L if it is a designated landmark or contributing building in a historic district and undergoes substantial rehabilitation costing at least 50 percent of the Assessor's pre-rehab market value. The owner must first get the building's municipality, or the County Board for unincorporated property, to adopt an ordinance or resolution backing the project and accepting the preservation commission's recommendation that the work meets federal rehabilitation standards. The reduced assessment runs 12 years and can be renewed.
Violations & Fines
Skipping the required municipal or County Board resolution, or failing to complete substantial rehabilitation meeting the 50 percent investment threshold, disqualifies the property; the Assessor also revokes Class L status if triennial compliance reports are not filed on time.
Frequently Asked Questions
Does Class L apply to my home?
Who decides if a building counts as a landmark?
How long does the tax break last?
Sources & Official References
Other rules in Cook County
Compare Cook County to another location·View the Illinois historic preservation overview
See something wrong?
Help us keep this page accurate. If you notice an error or outdated information, let us know.