Overview of HB 3673
Introduced: February 14, 2025
Effective from:Rules due by July 1, 2026; first disclosures begin January 1, 2027 (if enacted)
Region(s): Illinois, United States
About HB 3673
Illinois House Bill 3673 proposes mandatory greenhouse gas (GHG) emissions disclosure for large corporations, closely tracking California’s SB 253 (HB 3673 Climate Corporate Accountability Act).
If passed, the law would create a state-administered public registry requiring major businesses to report their full emissions footprint—including Scope 3—on an annual basis. The bill emphasizes climate transparency and equitable policy alignment across state lines.
Criteria for compliance
All public or private companies with global annual revenue over $1 billion (consolidated basis). Reporting entities must conduct business in Illinois, regardless of entity structure or incorporation location.
Compliance timeline
- July 1, 2026: Secretary of State finalizes implementing rules and emissions registry
- January 1, 2027: First Scope 1 & Scope 2 report due (covering FY 2026)
- Within 180 days of S1/S2: First Scope 3 disclosure (FY 2026)
- Annually thereafter: Same cadence applies—Scopes 1 & 2 by Jan 1; Scope 3 within 180 days
Disclosure requirements
- Annual public disclosures of Scopes 1, 2, and 3 GHG emissions
- Must follow the GHG Protocol Corporate Standard + Scope 3 Standard
- Data submitted to and published on a state-run emissions registry
- Companies must clearly describe calculation methods, organizational boundaries, and data limitations
Key obligations
- Establish robust emissions tracking systems across all scopes
- Submit timely and verified reports per Illinois guidance
- Ensure public-facing transparency that aligns with both Illinois and California frameworks
Third-party assurance
Mandatory independent verification of all reported data. Minimum limited assurance required; the level and audit process will be defined in final rulemaking. Third-party assurance applies to all scopes, including Scope 3 emissions.
Penalties for non-compliance
- Enforced by the Illinois Attorney General’s office
- Bill authorizes significant civil penalties and injunctive relief
- Fine amounts and escalation measures will be detailed in implementing rules
