OSHA's HCS 2024 rollout has four separate compliance deadlines, not one. They split two ways: substances vs mixtures, and manufacturers/importers vs employers. The earliest (substance manufacturers) was May 19, 2026; the last (mixture employers) is May 19, 2028. Most employers should focus first on November 20, 2026, the substance employer deadline. There is no 2029 date.
This calendar reflects the four-month extension OSHA published in the Federal Register (FR Doc 2026-00653), which pushed each original date later to give the supply chain time to reclassify and redistribute updated Safety Data Sheets (SDSs) and labels.
At a glance: Four HCS 2024 deadlines. Substances: manufacturers May 19, 2026, employers Nov 20, 2026. Mixtures: manufacturers Nov 19, 2027, employers May 19, 2028. Most employers' first hard date is Nov 20, 2026. No 2029 date. All per the four-month extension (FR Doc 2026-00653). HCS 2024 has four staggered deadlines: substance manufacturers comply by May 19, 2026 and employers by November 20, 2026, while mixture manufacturers comply by November 19, 2027 and employers by May 19, 2028 — there is no 2029 deadline.
The Complete HCS 2024 Compliance Calendar
| Deadline | Who must comply | What they must do | Standard |
|---|---|---|---|
| May 19, 2026 | Manufacturers, importers & distributors of substances | Reclassify single-substance chemicals, issue updated SDSs and shipped labels per HCS 2024 | 29 CFR 1910.1200(j)(2)(i) |
| November 20, 2026 | Employers using substances | As necessary: update written HazCom program, alternative workplace labeling, and employee training for newly identified hazards | 29 CFR 1910.1200(j)(2)(ii) |
| November 19, 2027 | Manufacturers, importers & distributors of mixtures | Reclassify mixtures, issue updated SDSs and shipped labels | 29 CFR 1910.1200(j)(3)(i) |
| May 19, 2028 | Employers using mixtures | Final program, label, and training updates for mixtures | 29 CFR 1910.1200(j)(3)(ii) |
All four dates trace to the same final rule and its four-month extension (FR Doc 2026-00653). HCS 2024 aligns primarily to GHS Revision 7.
These are the federal dates. In 22 states they are not your dates. State Plans regulate private construction under their own rules and set their own schedules — Washington's employer date for substances was July 20, 2026 and has passed, Michigan's and Minnesota's rules land on that same date, Oregon's is June 1, 2027, and California has not adopted HCS 2024 at all. Before you build a schedule from the table above, read what each of the 22 state plans actually says.
Four staggered deadlines — substances first, mixtures ~18 months later
Most employers' first hard date is Nov 20, 2026 (substances). Dates per 1910.1200(j) as extended by FR Doc 2026-00653. No 2029 deadline.
Why OSHA Split Substances From Mixtures
A mixture's classification depends on the hazard data of its component substances. OSHA could not reasonably require formulators to classify mixtures before substance data under the new criteria existed. So the agency sequenced the deadlines:
- Substances first — single chemicals are reclassified and re-documented (2026).
- Mixtures second — formulators use the freshly updated substance data to reclassify their blends (2027 for manufacturers, 2028 for employers).
The roughly 18-month gap between the substance track and the mixture track is intentional, giving the downstream supply chain time to receive updated component information before re-doing every mixture SDS and label.
What "Manufacturer" vs "Employer" Means for Your Dates
The two earlier dates in each track (May 19, 2026 and November 19, 2027) bind chemical manufacturers, importers, and distributors — the parties who classify and ship chemicals. They produce HCS 2024-compliant shipped container labels under 1910.1200(f)(1) and updated SDSs.
The two later dates (November 20, 2026 and May 19, 2028) bind employers — the parties who use chemicals in the workplace. By their respective deadlines, employers must:
- Update the written hazard communication program
- Update workplace/secondary container labels (1910.1200(f)(6) offers two options: full GHS label, or product identifier plus words, pictures or symbols giving at least general information on the hazards)
- Retrain employees on any new hazard classes, label elements, and SDS changes
- Verify incoming SDSs and shipped labels are HCS 2024-compliant
What Changed in HCS 2024 (and Why Training Is Required)
HCS 2024 adds and refines several hazard classes. Employees must be retrained on anything new before the applicable employer deadline:
- Chemicals Under Pressure — new hazard class at Appendix B.3.2
- Aerosols — now Categories 1-3 (Category 3 is non-flammable)
- Desensitized Explosives — Appendix B.17
- Updated classification and SDS criteria aligned to GHS Rev 7
Employer Action Plan by Date
Before November 20, 2026 (Substances)
- Audit your SDS library and flag substance SDSs still on older GHS revisions
- Request HCS 2024-compliant SDSs for single-substance products from suppliers
- Update your written HazCom program to reference HCS 2024 criteria
- Re-label substance secondary containers using a 1910.1200(f)(6) option
- Retrain employees on new hazard classes and label changes
- Document training attendance, SDS receipt dates, and label updates
Before May 19, 2028 (Mixtures)
- Confirm mixture suppliers reclassified by their November 19, 2027 deadline
- Collect updated mixture SDSs and verify shipped labels
- Re-train on any mixture-specific classification changes
- Finalize written program and workplace labels for mixtures
Penalties for Missing a Deadline
Hazard Communication ranked second on OSHA's FY2025 list of most-cited standards. For 2026, civil penalty maximums are frozen at 2025 levels (no inflation increase):
| Violation type | 2026 penalty |
|---|---|
| Serious (max) | $16,550 per violation |
| Willful (min / max) | $11,823 / $165,514 |
| Repeated (min / max) | $4,256 (Field Operations Manual policy floor, not set by 1903.15(d)) / $165,514 |
Beat November 20, 2026 without the fire drill
The substance employer deadline is a program-plus-labels-plus-training update. HazComFast flags SDSs on older GHS revisions, refreshes your written program, generates the delta training, and logs it — so each HCS 2024 date is a checklist, not a scramble. Start free, then run the transition across your sites on trial.
The standard, tools & related reading
- The standard: Hazard Communication — 29 CFR 1910.1200 (construction via 1926.59)
- Plan the work: HCS 2024 Deadline Lookup · HazCom Program Generator · SDS Gap Analyzer
- Related guides: Complete OSHA HazCom 2026 Guide · Mixtures 2027–2028 Transition · HCS 2024 Retraining by Nov 20, 2026 · GHS Rev 7 Converter
- 2026 OSHA penalty schedule · penalties by state
Frequently Asked Questions
What are the HCS 2024 compliance deadlines?
There are four staggered dates. Substance manufacturers/importers must comply by May 19, 2026, and employers using substances by November 20, 2026. Mixture manufacturers/importers must comply by November 19, 2027, and employers using mixtures by May 19, 2028. These reflect the four-month extension published in FR Doc 2026-00653 and are written in 29 CFR 1910.1200(j)(2) and (j)(3).
What is the difference between the substance and mixture deadlines?
OSHA phased compliance because reclassifying single substances is faster than reclassifying mixtures, which depend on updated substance data first. Substances come due in 2026 (29 CFR 1910.1200(j)(2)); mixtures follow roughly 18 months later in 2027 (manufacturers) and 2028 (employers) (1910.1200(j)(3)).
Does the November 20, 2026 deadline apply to my construction company?
It depends on the state. November 20, 2026 is the federal employer compliance date for substances, and it governs wherever federal OSHA enforces. Construction is covered through 29 CFR 1926.59, which incorporates 1910.1200 by reference. But 22 State Plans regulate private construction under their own rules and write their own schedules: Washington set July 20, 2026, and on the face of their rules Michigan and Minnesota land on that same date, so all three have already passed. Oregon set June 1, 2027. California has not adopted the 2024 update at all. Check your state plan's own rule before you plan to November 20.
Is there a 2029 HCS deadline?
No. The final HCS 2024 compliance date is May 19, 2028, for employers using mixtures (29 CFR 1910.1200(j)(3)(ii)). There is no 2029 deadline.
What standard governs these HazCom deadlines?
The Hazard Communication Standard at 29 CFR 1910.1200. The 2026 four-month extension to the compliance dates was published in the Federal Register as FR Doc 2026-00653.
OSHA figures and citations here come from our regulatory source-of-truth modules, last checked against the eCFR, OSHA.gov, and the Federal Register on October 5, 2026. Last reviewed October 5, 2026.
About This Article
Published by: HazComFast
Published: June 25, 2026
Last Updated: October 5, 2026
- https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1200
- https://www.osha.gov/hazcom
- https://www.federalregister.gov/documents/2024/05/20/2024-08568/hazard-communication-standard
- https://www.federalregister.gov/documents/2026/01/15/2026-00653/hazard-communication-standard
- https://www.osha.gov/stateplans
This content is for informational purposes only and does not constitute legal advice.