OSHA's Mixture SDS Deadline Is 13 Months Away: Start Updating Now

Chemical manufacturers, importers, and distributors have until November 19, 2027, to update their Safety Data Sheets (SDSs) and labels for mixtures under OSHA's revised Hazard Communication Standard (HCS 2024).

With about 13 months left, companies that sell mixtures should begin reviewing their SDS libraries now rather than wait for the final quarter.

The deadline was originally July 19, 2027. OSHA pushed it back by four months in a Federal Register notice published January 15, 2026, citing delays in finishing its compliance guidance. The agency moved every HCS 2024 deadline by the same amount so the tiered schedule stayed intact.

Why Mixtures Need Attention Now

The substance deadline has already passed. Manufacturers, importers, and distributors had until May 19, 2026, to update SDSs and labels for single substances, so revised supplier SDSs for raw materials should already be in circulation.

Those updated ingredient SDSs are the starting point for reclassifying a mixture. A formulator can't finalize a mixture's hazard classification until it has current data for every component. Companies with large product portfolios will need time to gather revised supplier SDSs, rerun classifications, and reissue documents.

The workload is significant because many common commercial products are mixtures: cleaners, solvents, paints and coatings, adhesives, lubricants, and fuels.

What Changes on a Mixture SDS

HCS 2024 aligns OSHA's rules mainly with Revision 7 of the UN Globally Harmonized System (GHS), with some elements of Revision 8. When updating an existing mixture SDS, preparers should check for these changes:

• Revised hazard classes: Desensitized explosives is a new hazard class. The aerosols class now includes non-flammable aerosols and a new "chemicals under pressure" category, and the flammable gases class adds categories for unstable gases.
• Broader classification scope: Classification must now account for hazards from a change in a chemical's physical form and from reaction products tied to known or reasonably anticipated uses. These hazards appear in Section 2.
• Trade secrets: Companies can now withhold an ingredient's concentration range, not just its exact percentage, as a trade secret. If they do, Section 3 must show one of OSHA's prescribed concentration ranges, which match Canada's.
• Updated precautionary and hazard statements: Label and SDS wording has been revised to reflect the new classes and categories.

The rule also adds labeling flexibility, with conditions. Containers of 100 ml or less may carry an abbreviated label, but only where the supplier can demonstrate that pull-out labels, fold-back labels, or tags with the full label information are not feasible. Containers of 3 ml or less may show just the product identifier if any label would interfere with normal use.

In both cases, the immediate outer package must carry the full label, along with a statement that the small containers must be stored in that package when not in use. Separately, containers already released for shipment don't need relabeling, provided the updated label travels with each shipment.

What Comes After the Deadline

Six months after the mixture deadline, on May 19, 2028, employers must update workplace labels, written HazCom programs, and employee training for mixtures. Employers can only do that once they receive accurate, current SDSs from their suppliers, so late updates upstream push compliance risk onto every customer downstream.

HCS 2024 also clarifies that employers may store SDSs in a way that groups hazardous chemicals by work area, but every product still needs its own individual SDS.

Until November 19, 2027, OSHA lets companies comply with the 2012 standard, the 2024 standard, or both. After that date, every mixture SDS and label must meet HCS 2024.

For employers, the nearer deadline is November 20, 2026, when workplace updates for substances are due. Our earlier coverage explains what that deadline requires.

Companies that author their own SDSs can use SDS authoring software to reclassify mixtures and reissue GHS Rev 7-compliant documents across a product portfolio. Companies that rely on supplier SDSs can track revisions in a centralized SDS library and flag outdated sheets before the deadline arrives.

References:

• Federal Register, "Hazard Communication Standard" (extension of compliance dates), January 15, 2026
• OSHA, "HCS 2024 Compliance Date Extension Notice"
• Federal Register, "Hazard Communication Standard" final rule, May 20, 2024