The Pipeline and Hazardous Materials Safety Administration (PHMSA) has published multiple changes to the Hazardous Materials Regulations. This is part of the DOT’s program to remove obsolete rules and reduce compliance costs without impacting safety. The most recent changes are discussed below and become effective September 3, 2026:
Registration & Record Keeping
Paying Haz Mat Registration Fees
This change modernizes the payment system for hazardous materials transportation registration fees by eliminating the option to pay by paper check and requiring electronic payment through the U.S. Department of Transportation e-Commerce internet site. PHMSA is taking this action to advance the goals of Executive Order (E.O.) 14247 (Modernizing Payments To and From America’s Bank Account) which directs that, as soon as practicable and to the extent permitted by law, all payments to the Federal Government must be processed electronically.
Recordkeeping Requirement
PHMSA is revising 49 CFR 107.620 to allow motor and vessel carriers to carry their PHMSA registration certificate, or a document showing their registration number, in either electronic or paper form. Carriers must make these documents available upon request to authorized enforcement and inspection personnel, regardless of whether they are in electronic or paper form.
Emergency Response Information
PHMSA is adding the option to maintain emergency response information in an electronic format rather than requiring a hard copy printed on paper. Carriers and facility operators are responsible for ensuring the reliability of their chosen method. A lack of cellular signal, device power loss, or device failure will not excuse compliance with the hazardous materials regulations.
General Changes
Definition of an Aerosol
PHMSA is revising the definition of an aerosol in § 171.8 to align with the international definition and it longer requires that an aerosol container be designed for the sole purpose of expelling a liquid, paste or powder.
Limited Quantity
Limited Quantity packages can use a reduced sized limited quantity marking on a package shipping label for certain shipments of hazardous materials in modes other than aircraft. PHMSA is also revising 49 CFR 173.25(a)(6) to specifically state that this marking is not authorized on an overpack.
Hazardous Substances
PHMSA is modifying how hazardous substances and their reportable quantities are listed within the Hazardous Materials Regulations. Specifically, rather than maintaining a duplicative list found in Tables 1 and 2 to Appendix A of 49 CFR 172.101, PHMSA is amending Appendix A to reference the EPA list directly. The EPA list can be found at 40 CFR 302.4 In addition, PHMSA is revising the definitions of ‘‘hazardous substance’’ and ‘‘reportable quantity (RQ)’’ to reference the EPA list in a seamless manner. Finally, PHMSA is making a conforming revision to the requirements for empty packagings to reflect the newly modified structure of Appendix A.
Material of Trade (MOT) Exception
This change increases the maximum allowable quantities of lithium batteries that can be transported as MOTs. This allowance applies to domestic companies in sectors such as construction, landscaping, mowing, tree service, food service, and entertainment—enabling them to carry the power sources required to perform their trade safely and more efficiently.
The regulations currently limit the aggregate gross weight of materials of trade—other than certain diluted mixtures of Class 9 materials—in a motor vehicle to 200 kg (440 pounds). This revision increases this allowance for lithium batteries by authorizing up to 30 kg (66 pounds) per battery, a 500 kg (1102 pounds) gross vehicle limit, and no limit for batteries installed in equipment, while including safety provisions to prevent short circuits, shifting damage, and accidental activation.
Special Permits
Special Permit Packaging
PHMSA is allowing DOT Special Permit packaging to be used for the duration of their usable life regardless of the status of the grantee and whether the Special Permit was not renewed—e.g., when the original grantee has gone out of business but some of their packaging remain in commerce because a shipper has yet to use it for hazardous material shipment.
Special Permit Approval and Renewal
An application to renew a special permit can be filed any time on or before its expiration date, rather than requiring the renewal application to be filed 60 days in advance. PHMSA has transitioned to an electronic system and can process renewal applications far more efficiently and no longer needs the 60-day lead time.
Emptying Certain Packaging Types
PHMSA is adopting the provisions of DOT Special Permits 12412 (IBC intermediate bulk containers) and 11646 (DOT specification drums) into the Hazardous Materials Regulations. The adoption of these special permits will authorize the discharge (i.e., emptying) of certain hazardous materials from specified packaging types without first removing the packaging from the vehicles on which they are transported. Safety controls, including attendance by a qualified person during unloading, not allowing the manifolding of multiple packages, and requiring that hoses are not attached to outlets during transportation are required. These special permits have been in place for over 20 years and have a well-established safety record.
Transportation of Refrigerating Machines
PHMSA is adopting the provisions of DOT Special Permit 21287 into the Hazardous Materials Regulations by revising 49 CFR 173.307(a)(4) to provide an exception for the transportation of refrigerating machines containing certain low flammability refrigerant gases. This revision expands the existing exception to include refrigerating machines that use a refrigerant that is a Category 1B refrigerant as specified in the Globally Harmonized System (GHS) of Classification and Labelling of Chemicals (which PHMSA is incorporating by reference) or a Group A2L refrigerant as specified in American National Standards Institute/American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ANSI/ ASHRAE) Standard 34. PHMSA is also incorporating by reference ANSI/ ASHRAE Standard 34–2024, ‘‘Designation and Safety Classification of Refrigerants,’’ which refers users to the list of flammable gases eligible for this exception.
PHMSA is also adopting the provisions of DOT Special Permit 21379 into the Hazardous Materials Regulations by revising 49 CFR 173.306 to streamline the transportation of refrigerating machines containing certain low flammability refrigerant gases. This revision allows up to 5,000 lbs. of low flammability refrigerants in refrigerating machines if they are a Category 1B refrigerant as specified in the Globally Harmonized System (GHS) of Classification and Labelling of Chemicals (which PHMSA is incorporating by reference) or a Group A2L refrigerant as specified in American National Standards Institute/American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ANSI/ ASHRAE) Standard 34. PHMSA is also incorporating by reference ANSI/ ASHRAE Standard 34–2024, Designation and Safety Classification of Refrigerants, which refers users to the list of flammable gases eligible for this exception.
Empty (Residue) IBC Containers
PHMSA is adopting the provisions of DOT Special Permit 21478 into the Hazardous Materials Regulations by revising 49 CFR 173.29 to add a new subparagraph (d) that authorizes the transportation of ‘‘empty’’ IBCs only containing a residue of a hazardous material in a manner similar to what is already allowed for empty non-bulk packaging in 49 CFR 173.29(c). PHMSA is also making conforming revisions to 49 CFR 172.331, 172.504, and 172.514. These revisions include amending 49 CFR 172.514 to make clear that IBCs shipped in accordance with the conditions of the empty packaging exception are not subject to placarding. The new provisions will require a document (in paper or electronic form) to accompany the IBCs that denotes the phrase ‘‘Residue IBC(s)’’ and indicates the number of IBCs containing hazardous materials for each Class or Division of material transported on a transport vehicle.
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