OSHA HCS 2024: the 20 November 2026 employer deadline for substances is close

What changed

The May 2024 revision of the Hazard Communication Standard aligned it with GHS Revision 7 and changed classification, label and SDS requirements. In January 2026 OSHA extended the compliance dates by four months after industry feedback that guidance had arrived too late.

The revised schedule:

By now, updated substance SDSs and labels should already be arriving from suppliers. The open item for most companies is the employer duty for substances, due 20 November 2026.

Who is affected

• Every US employer with hazardous chemicals in the workplace — the employer duties are not limited to chemical companies
• Sites receiving reclassified substances, new hazard statements, or changed pictograms and signal words
• Suppliers to the US who have not yet completed the substance transition

Why this matters

HCS 2024 is not only a document swap. A reclassified substance can trigger new workplace obligations: a changed workplace label, an updated written programme, and additional training where a newly identified hazard is now communicated. Substance and mixture deadlines are separate, so a mixed inventory needs a phased plan rather than a single cut-over.

Recommended actions

• Compare each updated supplier SDS against the version it replaces; record what changed in Sections 2, 3, 9, 10 and 11.
• Audit workplace labels against the current classification and re-label where the hazard information changed.
• Update the written hazard communication programme to reflect the new SDS and label content.
• Deliver training on any newly identified hazard before staff are exposed, and keep the training records.
• Assemble inspection-ready documentation: the SDS comparison, the label audit, the programme revision and the training log.
• Track the mixture deadline (19 November 2027) separately so it is not missed once the substance work is done.