Data / Federal rules / 2026-09905
Revision of Tier 4 Criteria Pollutant Standards, Part 1: Amendments to Phase-In Schedule for Light-Duty and Medium-Duty Vehicles
The Environmental Protection Agency published this proposed rule in the Federal Register on May 18, 2026. Comments closed on July 6, 2026.
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What the agency says
The U.S. Environmental Protection Agency (EPA) is reconsidering the Tier 4 criteria pollutant standards for new motor vehicles promulgated within the final rule entitled "Multi-Pollutant Emissions Standards for Model Years 2027 and Later Light-Duty and Medium-Duty Vehicles." This reconsideration will occur in two separate, but coordinated, rulemakings. In this Part 1 rulemaking, the EPA is proposing to amend the phase-in schedule for the Tier 4 criteria pollutant standards for certain vehicles to address changing circumstances and feasibility concerns. These amendments, if finalized, would extend the Tier 3 standards for certain vehicles to model years (MYs) 2027 and 2028 such that the Tier 4 standards for these vehicles would phase in starting with MY 2029. The EPA is also proposing other changes to the test protocols used to evaluate emissions performance for certification and related regulatory issues. Potential amendments to the Tier 4 standards and other program elements will be proposed separately in a future Part 2 rulemaking.
Key facts
- Document number
- 2026-09905
- Type
- Proposed rule
- Action
- Proposed rule
- Agency
- Environmental Protection Agency
- Published
- May 18, 2026
- Comments due
- July 6, 2026
- Dates
- Comments. Comments must be received on or before July 6, 2026, at 11:59 p.m. Eastern Time. Comments on the information collection provisions submitted to the Office of Management and Budget (OMB) under the Paperwork Reduction Act (PRA) are best assured of consideration by OMB if OMB receives a copy of your comments on or before July 6, 2026.
- Docket
- EPA-HQ-OAR-2025-3297; FRL-13030-01-OAR
- Regulation ID (RIN)
- 2060-AW96
- Code of Federal Regulations
- 40 CFR 85; 40 CFR 86; 40 CFR 1066
- Topics
- Administrative practice and procedure; Air pollution control; Confidential business information; Environmental protection; Imports; Incorporation by reference; Labeling; Motor vehicle pollution; Reporting and recordkeeping requirements; Research; Warranties
- Pages
- 25
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Read from the Federal Register API, last updated 2026-10-23. The document on federalregister.gov is the official record; dates and dockets can change through later corrections. Free to reuse with credit to SpecStream under CC BY 4.0.