Special Assessment for Solar Energy Systems

March 16, 2023


Illinois offers a special assessment of solar energy systems for property tax purposes. When a claim for alternate valuation is filed, the chief county assessment officer is required to ascertain two values: the value of the improvements as if equipped with a conventional heating or cooling system and the value of the improvements as equipped with the solar energy system. The alternate valuation is the lesser of these two values.

Eligible equipment includes both active and passive solar energy systems. The exemption is not valid for equipment that is equally usable in a conventional energy system or for components that serve non-solar energy generating (e.g., structural, aesthetic, insulating, etc.) purposes.

This exemption also does not apply to commercial solar energy systems in counties with fewer than 3,000,000 inhabitants. "Commercial" in this context refers to systems that generate electricity primarily for wholesale or retail sale, not on-site use; the definition does not refer to customer class.

Application for Solar Assessment

Those who wish to have their solar energy property valued in this fashion must file the State of Illinois PTAX-330 property tax form with their local county assessor's office. Forms are available online and through each Illinois county assessor's office.

Program Overview

Implementing Sector: State
Category: Financial Incentive
State: Illinois
Incentive Type: Property Tax Incentive
Web Site:
Administrator: Illinois Department of Commerce and Economic Opportunity
Start Date:
Eligible Renewable/Other Technologies:
  • Solar Water Heat
  • Solar Space Heat
  • Solar Photovoltaics
Incentive Amount: Varies
Maximum Incentive: None specified
Eligible System Size: None specified
Equipment Requirements: None specified


Name: § 35 ILCS 200/10-5 et seq.


Name: Kara Moretto
Organization: Illinois Department of Revenue
Address: Willard Ice Building
Springfield IL 62702
Phone: (800) 732-8866
Email: kara.moretto@illinois.gov
Name: Public Information
Organization: Illinois Department of Revenue
Address: Willard Ice Building
Springfield IL 62702
Phone: (800) 732-8866

This information is sourced from DSIRE; the most comprehensive source of information on incentives and policies that support renewables and energy efficiency in the United States. Established in 1995, DSIRE is operated by the N.C. Clean Energy Technology Center at N.C. State University.