AIM Act 40 CFR Part 84: Legislative Foundation and Subpart C Overview

What Is the AIM Act and Where Did It Come From?

The AIM Act was enacted on December 27, 2020, as Section 103, Division S of the Consolidated Appropriations Act, 2021 (H.R. 133). It is codified at 42 U.S.C. § 7675 and grants EPA new HFC authority that sits outside the existing Clean Air Act framework — a deliberate structural choice that gave EPA a cleaner statutory hook for HFC regulation after earlier SNAP-rule litigation.

The legislation received broad bipartisan support, a rare outcome for domestic climate-adjacent regulation. Industry support was significant: refrigerant producers, HVAC manufacturers, and supermarket chains had all been operating with regulatory uncertainty following the D.C. Circuit's 2017 ruling in Mexichem Fluor v. EPA, which struck down an earlier EPA attempt to phase out HFCs under Section 612 of the Clean Air Act. The AIM Act resolved that uncertainty by providing unambiguous congressional authorization.

The Act also established the domestic legal architecture needed once the U.S. moved toward ratifying the Kigali Amendment to the Montreal Protocol — which the Senate approved in October 2022. Without the AIM Act, EPA would have had no clear authority to implement the HFC phasedown commitments the amendment requires.

The Three Regulatory Pillars of the AIM Act

The AIM Act gives EPA authority through three distinct subsections, each targeting a different point in the HFC supply chain. EPA implemented each as a separate subpart of 40 CFR Part 84, with different regulated entities, compliance timelines, and enforcement mechanisms.

Most facility operators and compliance officers work primarily within Subpart C — the pillar that governs what happens to HFCs once they are already in equipment. Subparts A and B primarily affect HFC producers, importers, and equipment manufacturers.

The HFC Phasedown Schedule: Statutory Baselines and Step-Down Dates

The HFC phasedown schedule and allowance step-down dates are anchored to a baseline calculated from average U.S. production and consumption during 2011–2013, plus percentages derived from historical CFC and HCFC production. Allowances are denominated in Metric Tons of Exchange Value Equivalents (MTEVe), with each HFC weighted by its global warming potential (GWP) per IPCC AR4.

The 85% reduction target by 2036 mirrors the Kigali Amendment's developed-country trajectory. The allowance trading program under Subpart A creates a market mechanism that incentivizes phasedown without mandating specific technology choices — but for compliance officers managing equipment in the field, the operational impact shows up through rising HFC costs and, eventually, refrigerant availability constraints.

How 40 CFR Part 84 Subpart C Implements AIM Act Subsection (h)

Subpart C was published as the Emissions Reduction and Reclamation (ER&R) final rule on October 11, 2024, in Docket EPA-HQ-OAR-2022-0606. First provisions take effect January 1, 2026.

Coverage extends to appliances with a full charge of 15 or more pounds of HFC refrigerant, or HFC substitutes with a GWP above 53. That threshold — lower than the 50-pound threshold under Section 608 — brings a large population of rooftop units, split systems, and walk-in coolers into the regulatory perimeter for the first time.

The key Subpart C sections compliance officers need to know:

• § 84.106 — Leak repair requirements, including trigger thresholds, repair timelines, and recordkeeping obligations
• § 84.108 — Automatic leak detection system requirements for applicable equipment categories
• § 84.110 — Fire suppression data collection and reporting
• § 84.112 — Reclamation reporting for reclaimers, distributors, and wholesalers

The rule covers the full equipment lifecycle: installation, servicing, repair, maintenance, and disposal. Obligations attach to the owner/operator of covered appliances, not to the service contractor.

Subpart C vs. Section 608: What Changed for Compliance Officers

For compliance officers already familiar with Section 608 (40 CFR Part 82, Subpart F), Subpart C will feel conceptually similar but with several material differences. Read a full breakdown of how Subpart C differs from the Section 608 refrigerant management rules, but the headline changes are:

• Statutory hook: Section 608 derived authority from the Clean Air Act to address ozone-depleting substances. Subpart C uses the AIM Act's independent authority (42 U.S.C. § 7675(h)) to address HFCs — substances that are not ozone-depleting but are potent greenhouse gases.
• Coverage threshold: Section 608 applied to systems with 50 or more pounds of ODS refrigerant. Subpart C applies to appliances with 15 or more pounds of HFC refrigerant or HFC substitutes with GWP above 53.
• Leak rate thresholds: Subpart C establishes affirmative 10% annualized leak rate thresholds for comfort cooling, refrigerated transport, and other covered appliance categories, with mandatory repair timelines triggered when those thresholds are exceeded.
• Reporting structure: Subpart C introduces structured reporting obligations beginning January 1, 2026, with reclaimers, distributors, and wholesalers facing a February 14, 2027 deadline for their first annual report covering CY 2026 data.

Section 608 obligations for ODS-containing equipment remain in place alongside Subpart C. Facilities with older R-22 systems may be subject to both regulatory frameworks simultaneously.

Key Compliance Deadlines Every Compliance Officer Must Know

Subpart C introduces a staggered compliance calendar. Missing an early deadline does not simply result in a late penalty — it can trigger a cascade of reporting deficiencies that compound enforcement exposure.

Enforcement Authority and Penalty Exposure

The AIM Act enforcement framework is not independent — it plugs into Clean Air Act Sections 113, 114, 304, and 307. Violations of Subpart C are subject to federal civil penalties under CAA § 113, which means the same penalty-per-day structure used in ODS enforcement now applies to HFC management.

According to the EPA's AIM Act enforcement page, enforcement targets include: importing or producing HFCs without allowances, false or misleading reporting, improper labeling, and technology transition violations. EPA has taken more than 30 enforcement actions since 2023, including settlements with Resonac America, Hudson Technologies, and Carrier InterAmerica.

An Expedited Settlement Agreement (ESA) pilot program exists for first-time, easily corrected violations below a penalty threshold. This provides a defined path for entities that self-identify and promptly correct compliance failures — an important tool for compliance officers managing a new regulatory framework.

The Kigali Connection: International Treaty as Legislative Context

The Kigali Amendment (2016) to the Montreal Protocol sets an 85% reduction target for developed countries by 2036 — the trajectory the AIM Act's phasedown schedule mirrors. (A separate, slower schedule applies to developing-country Article 5 parties, reaching 80–85% reduction by 2047.) The U.S. ratified the amendment on October 26, 2022, with cross-sector industry support. For a full examination of the treaty mechanics, see the Kigali Amendment context and its effect on U.S. HFC obligations.

The structural point compliance officers should know: the AIM Act predates Kigali ratification by nearly two years. Congress passed enabling domestic legislation before the Senate ratified the treaty, which means 40 CFR Part 84 is simultaneously domestic environmental law and international treaty implementation. The phasedown schedule in 40 CFR Part 84 Subpart A is calibrated to meet Kigali commitments, and the ER&R framework in Subpart C supports those commitments by minimizing HFC emissions throughout the equipment lifecycle.

Compliance officers should treat 40 CFR Part 84 as a durable regulatory framework, not a transitional one. The treaty architecture, bipartisan legislative support, and industry alignment behind the AIM Act make material rollback unlikely — and the phasedown steps already baked into the statute will continue tightening through 2036 regardless of EPA rulemaking activity.

Sources

• EPA — Background on HFCs and the AIM Act
• 42 U.S.C. § 7675 — American Innovation and Manufacturing Act (U.S. House, uscode.house.gov)
• Federal Register — ER&R Final Rule (Oct. 11, 2024, Docket EPA-HQ-OAR-2022-0606)
• EPA — Reporting Resources for the Emissions Reduction and Reclamation Rule
• EPA — Enforcement of the AIM Act
• Federal Register — Establishing the HFC Allowance Allocation and Trading Program (Oct. 5, 2021)
• EPA — Frequent Questions on the Phasedown of Hydrofluorocarbons
• Congress.gov — AIM Act Legislative Text (Consolidated Appropriations Act, 2021, H.R. 133)