IUCLID 6 explained, from download to a REACH-IT submission

IUCLID 6 is ECHA's free software for recording chemical properties and hazards and preparing regulatory dossiers (IUCLID 6 project). For REACH registration, prepare your dossier in IUCLID, check it, then submit it through REACH-IT.

"IUCLID 6" is the product name, not the current release number. Version 10 was released on 27 April 2026 with format changes (ECHA).

What IUCLID 6 is used for

REACH Article 111 requires the technical dossier in IUCLID format, and ECHA coordinates that format with the OECD (REACH Regulation). IUCLID was the first system to fully implement the OECD Harmonised Templates, the standard formats for reporting chemical test data.

The same software also covers:

• CLP, including poison centre notifications in PCN format, and SCIP (ECHA cloud services).
• Biocide dossiers, prepared in IUCLID and submitted through R4BP 3.
• Plant protection product and MRL dossiers for EFSA, prepared in IUCLID format ("IUCLID for EFSA") and submitted through the ECHA Submission portal (ECHA).
• Drinking Water Directive notifications, sent as .i6z files through the ECHA Industry Portal, open since 5 January 2026 (ECHA).

Cloud, Desktop or Server

All three are free. Pick by how many people touch the data.

ECHA hosts Cloud with up to 5 GB of storage, managed backups and helpdesk support at no charge (ECHA cloud services). It is open to registrants of all sizes, not just SMEs. For local installations, ECHA's registration guide explains the Desktop and Server options.

IUCLID 6 download and releases

Desktop and Server installers are on the IUCLID download page, under a licence agreement. You have to sign in on the site before the files will download. Check the page for the current version 10 build before you install.

ECHA plans a major release each spring and a service release each autumn. The planned releases page lists a service release for 26 October 2026. Major releases can change the format, and your dossier must match the format version the submission system accepts. So check that page before any deadline, not the week of it.

IUCLID 6 user manual, training and reference substances

The "Functionalities of IUCLID 6" manual sits in the help system and on the documentation page. For the regulatory side, ECHA's manuals give step-by-step instructions for REACH, CLP, biocides and DWD dossiers, and they're built into IUCLID too. The report generator exports IUCLID data as PDF, RTF, CSV or XML, including chemical safety report sections.

For IUCLID 6 training, ECHA runs a webinar for each major release: version 9 on 28 May 2025 and version 10 on 12 May 2026. Recordings and Q&A are on the ECHA events pages, including the version 9 webinar Q&A.

A reference substance is an electronic record, not a physical sample. It stores identifiers and structure once in the IUCLID database, so you can link it from any section and reuse it across datasets. Ready-made ones can be downloaded from the IUCLID site.

From IUCLID dataset to dossier

You enter data in a substance dataset. "Dossier creation" then makes a read-only copy of it, with administrative details that identify the submission type (ECHA).

Run the Validation Assistant on the dataset and again on the finished dossier. But a clean report still isn't a guarantee: "The manual verifications done by ECHA staff are not displayed in the Validation assistant report."

The dissemination preview, installed with IUCLID 6, shows what would go public based on your confidentiality claims. ECHA still assesses them. Information covered by an inadequately justified claim can be published (ECHA manual).

Finally, export the dossier as an .i6z file. Cloud users can skip the file and pick "Select from IUCLID Cloud" in the REACH-IT wizard (ECHA).

Submitting in REACH-IT

REACH-IT is ECHA's system for submitting dossiers and communicating with ECHA. Company accounts are managed in ECHA Accounts. EU Login is required only for new authority users. REACH registrations still go through REACH-IT, not the ECHA Industry Portal.

Before you register, Article 26 requires an inquiry for a non-phase-in substance, and for a phase-in substance that was not pre-registered. If that substance was registered less than 12 years earlier, ECHA gives you the earlier registrants' names so data can be shared (REACH).

A joint submission is not a step in every registration. The lead registrant creates it in REACH-IT, submits the shared data first and shares a security token. Members join with the token and submit their own dossiers referring to the lead dossier (ECHA).

After you upload, the business rules check decides whether ECHA can process the dossier. Passing it gives a submission number, not a registration number. The technical completeness check follows, and the fee invoice arrives in REACH-IT (ECHA).

REACH Article 20 requires the completeness check within three weeks of the submission date. It checks that the required elements are there and the fee is paid, not data quality. If you miss the deadline to complete the dossier, ECHA rejects the registration. The registration number is assigned once the dossier is complete and the fee is paid, and the registration date is the submission date. After a failed technical completeness check, only one additional submission attempt is allowed.

What the public dossier data shows

Published REACH registration data now lives in ECHA CHEM, along with the C&L Inventory. The old pages for REACH registration data, the C&L Inventory and Brief Profiles were decommissioned on 18 December 2025. Since 12 February 2026 you can download the full list of REACH registered substances from ECHA CHEM.

REACH Article 119 lists what is always published free online: classification and labelling, physicochemical and fate data, the result of each toxicological and ecotoxicological study, DNELs and PNECs, and safe-use guidance. Tonnage band, study summaries, trade names and purity are published unless a confidentiality claim is accepted. For a bulk download, REACH Study Results is the closest thing to a public IUCLID database: a set of dossiers in IUCLID format with non-confidential study data, refreshed in June 2026. The download asks you to accept terms of use.

Reading published data does not let you reuse the studies in your own dossier. You need the full study report or a letter of access, apart from the Article 25(3), 27(6) and 30(3) exceptions.

UK REACH

GB registrations go through "Comply with UK REACH", and "Dossiers must be submitted in IUCLID ... format" (HSE). GOV.UK asks for .i6z files from IUCLID 6 or later, plus a Government Gateway account and a Defra account (GOV.UK).

You can ask RegAffairs AI how IUCLID 6 and REACH-IT fit together and follow its citations into the REACH articles behind each step.