TAIWAN EXISTING CHEMICAL COMPLIANCE
A company that has obtained an existing chemical substance standard registration completion number in Taiwan still needs to manage the information behind that registration. Depending on the substance, registration status and authority designation, its next steps may include updating manufacturing and use information and submitting hazard and exposure assessment data. Understanding these stages helps Taiwan manufacturers and importers plan their submissions and overseas suppliers anticipate the information their customers may request.
At CRAC China 2026, Ya-Hui Ni, General Manager of Environmental Resources & Information Co., Ltd. (ERI), examined Taiwan's evolving chemical substance management system, including supplementary information requirements for designated existing substances, actual use and exposure information, and plans for evaluating a second group of existing chemicals. This article connects those developments with the checks companies should make after standard registration.
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Taiwan Existing Chemical Compliance at a Glance
| Compliance stage | Main question | Practical focus |
|---|---|---|
| Substance identity | Is the substance listed on the Taiwan Chemical Substance Inventory (TCSI)? | Confirm the substance identity and relevant components of a mixture. |
| Phase 1 registration | Does the manufacture or import activity meet the applicable threshold? | Check the annual quantity, registrant and applicable registration timing. |
| Standard registration | Is the existing substance designated for standard registration, and does the quantity threshold apply? | Confirm the designated list, quantity band and registration status. |
| After the completion number | What hazard and exposure information remains to be registered? | Check Appendix 4, authority communications and any designated submission deadline. |
| Ongoing management | Are registered information and applicable reporting obligations current? | Review applicable quantity reporting, changes in use and new information relevant to the registration. |
| Additional controls | Has the substance subsequently been designated as a toxic or concerned chemical substance? | Assess applicable handling, approval, reporting and other controls separately. |
For an overview of the wider framework, including new chemical substances and occupational safety requirements, see REACH24H's Taiwan TCCSCA and OSHA chemical registration services.
Start with Substance Identity and Registration Status
Taiwan's chemical registration framework distinguishes new chemical substances from existing chemical substances. TCSI status is a starting point for that distinction, but it does not by itself answer every compliance question.
For an existing substance manufactured or imported at 100 kilograms or more in a year, Article 15 of the Regulations of New and Existing Chemical Substances Registration requires the registrant to apply for Phase 1 registration within six months of the triggering event. Companies should also assess applicable exemptions and the facts of their own activity.
For a mixture, a product-level trade name is rarely enough to establish the regulatory status of its components. The supplier and Taiwan importer should identify the relevant substances, confirm their identities and review the applicable registration and control requirements.
Phase 1 Registration and Standard Registration Serve Different Purposes
Phase 1 registration and existing substance standard registration should be tracked as separate stages.
Ni explained that the authority designates existing substances for standard registration in phases. For the first designated group, the framework covers 106 existing chemical substances and applies according to the designated list, quantity band and other conditions.
A Phase 1 registration number does not itself establish that a designated substance's standard registration has been completed. Conversely, a company should not assume that every substance listed on TCSI requires standard registration: the applicable designation and quantity thresholds need to be checked.
What Does a Standard Registration Completion Number Mean?
Under Article 18 of the registration regulations, the authority issues an existing substance standard registration completion number after the information specified in Appendix 3 has been registered. The registrant must then complete the Appendix 4 information proactively or by the deadline set by the authority.
This distinction matters because the completion number and the later assessment information represent different parts of the process:
| Information stage | What it establishes |
|---|---|
| Appendix 3 information | The substance and registration information submitted for standard registration and the basis for issuing the completion number. |
| Appendix 4 information | Hazard and exposure assessment information to be completed proactively or within an authority-designated period. |
At CRAC China 2026, Ni emphasized that follow-up work should reflect the registrant's actual manufacturing, use and exposure conditions. Companies should therefore retain the original registration records and know who can confirm whether the information still describes current operations.
Which Existing Substances Have Designated Assessment Deadlines?
Taiwan has advanced supplementary hazard and exposure information for selected substances from the first group of 106. The relevant deadlines apply to registrants within the authority's designation, not automatically to every company that supplies or uses a listed substance.
| Designated group | Substances | Main milestone for designated registrants |
|---|---|---|
| Four substances designated in 2025 | Antimony trioxide, sulfuric acid, toluene and zinc oxide | Complete the specified supplementary information by December 31, 2026. |
| Three substances designated in 2026 | Carbon black, 4,4′-methylenediphenyl diisocyanate (4,4′-MDI) and silicon carbide | Complete the designated supplementary information by December 31, 2027. |
The authority has reminded designated registrants of the four-substance deadline and made updated hazard assessment examples available through the Chemical Substance Registration Platform.
For the three substances designated in 2026, Ni described a separate preparation milestone: registrants that choose to prepare their own hazard assessment information should complete the relevant survey by December 31, 2026, before the designated supplementary submission deadline in 2027. Companies should check the authority's notice and their registration circumstances before selecting a route.
For the three-substance scope and action points, see Taiwan Chemical Registration: 2027 Hazard and Exposure Assessment Deadline.
These Two Designations Are Not the "Second Batch" of Existing Chemicals
The four-substance and three-substance arrangements concern supplementary assessment information for selected substances from the first group of 106. The second batch refers to a separate planning and screening exercise for additional existing substances.
Keeping the two workstreams separate prevents a common planning error: assuming that every substance appearing in a screening list has the same submission obligation or deadline as a designated registrant under the first group.
Hazard Assessment and Exposure Assessment: What Is the Difference?
The two assessments use related information but answer different questions.
Hazard assessment examines the substance's hazardous properties. Depending on the designated procedure, an authority-provided example may be available, or a registrant may prepare its own assessment information.
Exposure assessment considers the conditions under which people or the environment may encounter the substance. Those conditions can differ between registrants handling the same chemical. A common hazard assessment therefore does not replace the need to review the registrant's own exposure information.
Ni's explanation of the designated submission process points to two practical checks:
Confirm the hazard assessment route. Determine whether an official example is applicable and whether the registrant intends to use it or prepare its own information. Check any required confirmation or survey.
Review the exposure scenario. Review actual and anticipated manufacturing, formulation, storage and use activities, and prepare the applicable exposure scenario information in accordance with the designation.
For the designated process discussed by Ni, Item 9.1 exposure scenario information was the focus; Items 9.2 and 9.3 were not required at that stage. The authority specifies that designated registrants with actual or anticipated manufacturing, formulation or use activities must submit an Item 9.1 exposure scenario description. Companies should check the applicable instructions and their individual notice.
The applicable information requirements should be assessed against the actual operation. Companies should not infer their obligations solely from a description such as distributor or storage operator.
What Information Should Registrants Prepare?
Ni identified two connected areas of information: manufacture, use and exposure information and exposure scenario descriptions. Together, they help establish where and how the substance is handled.
| Information area | Examples to collect or confirm | Who may hold it |
|---|---|---|
| Substance and registration | Substance identity, registration number, completion number, quantity band and authority notices | Taiwan registrant; technical or regulatory team |
| Manufacture and import | Annual quantity, substance form, manufacturing method and relevant sites | Taiwan manufacturer or importer |
| Uses and life-cycle stages | Intended uses, product function, processing and relevant downstream activities | Registrant, overseas supplier and downstream customer |
| Worker exposure | Degree of enclosure, concentration, duration, operating temperature, ventilation and protective measures | Facility operations, EHS and technical teams |
| Environmental exposure | Handling quantity, release conditions, wastewater and waste-gas controls, and relevant treatment information | Facility operations and environmental management teams |
| Data access and confidentiality | Ownership of studies, permission to use data and arrangements for confidential information | Data owner, registrant and appointed representative |
The information needed for an individual submission depends on the applicable registration route and authority instructions. The table is a preparation tool; it should not be read as a universal list of mandatory documents for every company.
Why Item 2 and Item 9.1 Need to Be Consistent
Ni highlighted Item 2—manufacture, use and exposure information and Item 9.1—exposure scenario information as practical preparation priorities.
For example, if a substance is imported for use in a closed production process, the use description, degree of enclosure and operating controls should describe the same activity across the relevant records. If the product is later supplied for an additional use, the registrant should assess whether the registered information needs to be updated and whether further information is needed from the supply chain.
This review is especially relevant where the overseas supplier knows the formulation or intended function, while the Taiwan registrant and downstream facility hold the operational information.
Annual Reporting and Registration Updates Are Separate from Assessment Submissions
A designated hazard or exposure assessment deadline does not replace annual reporting.
Under Article 24, registrants of registered new and existing chemical substances report the previous year's manufactured or imported quantity annually, starting in the year following registration approval. The regulation specifies the reporting period as April 1 to September 30.
Registrants should also review the applicable rules for changes and supplementary information. For example, Article 29 addresses new scientific evidence, new use information and new hazard or exposure information, among other circumstances. The action and timing depend on the nature of the information and any authority communication.
A useful internal practice is to track these matters separately:
Annual quantity reporting: what was manufactured or imported during the previous year.
Registration changes: whether registered information needs to be changed under the applicable procedure.
Hazard and exposure information: whether Appendix 4 information has been completed and whether a designated deadline applies.
Authority notices: which substance, registrant and submission route a notice covers.
What Is Planned for the Second Batch of Existing Chemicals?
Ni described a risk-based screening approach for a further group of existing substances. The authority screened substances by quantity, hazard and exposure-related factors, identifying 28 candidates for priority information collection and evaluation. Ni explained that nine substances with relatively sufficient information were then selected from this group as candidates for the second batch of priority existing chemicals (PECs).
The 28 substances are a preliminary screening group. Selection of the nine candidates does not, by itself, mean that every company handling them has been designated to submit supplementary information. The final designation and applicable obligations depend on the authority's subsequent regulatory actions. See Taiwan's preliminary second-batch existing chemical substances list.
Ni also explained a proposed change in the division of work: the authority would take a more active role in collecting and evaluating available information, while designated registrants would provide supplementary data and information about actual use and exposure.
For companies, the immediate value is to identify whether substances in their portfolio appear in the candidate group and determine who holds reliable use, process and exposure information. Any future submission duty should be confirmed against the final rules and individual designation.
Registration and Additional Substance Controls Must Be Checked Separately
Standard registration provides information for chemical management. A substance may also be subject to separate controls if it is listed as a toxic or concerned chemical substance.
Ni described how regulatory assessment and screening can inform subsequent management. Depending on the substance and applicable rules, later controls may address activities such as manufacture, import, sale, use, storage, reporting or permitted uses.
A standard registration completion number should therefore be considered alongside—not in place of—an assessment of applicable controlled-substance requirements. The substance, concentration, activity and effective date all matter.
For an example of how a separate listing proposal is being developed, see Taiwan Consults on Proposed Listing of Six Concerned Chemical Substances. A proposal remains subject to the final published measure.
Frequently Asked Questions
How REACH24H Can Support Taiwan Existing Chemical Compliance
REACH24H has an office and local team in Taiwan, enabling closer coordination with Taiwan manufacturers, importers and overseas suppliers on regulatory questions, information collection and project communication. This local presence helps companies address the practical requirements of Taiwan chemical registration and subsequent data management.
Depending on the substance and project, our team can assist with TCSI and registration status checks, applicability and data-gap assessment, hazard and exposure information preparation, and coordination of registration or post-registration submissions.
Clarify Your Taiwan Registration and Assessment Requirements
Discuss your substance, registration status and intended use with REACH24H's Taiwan team to identify applicable requirements and information gaps.
Recommended Reading
Taiwan Chemical Registration: 2027 Hazard and Exposure Assessment Deadline
Taiwan Announces Preliminary List for the Second Batch of Existing Chemical Substances
Taiwan Consults on Proposed Listing of Six Concerned Chemical Substances
