The UK REACH Roadmap: Understanding Grandfathering and DUINs Under UK REACH

When UK REACH replaced EU REACH in Great Britain (GB), the regulatory position changed for many companies, with different transitional routes available depending on whether they held an EU REACH registration themselves or relied on one held by another company.

If you are new to UK REACH, we recommend starting with the first article in this series, which explains the fundamentals of the regulation and why it matters. You can find this here: UK REACH Roadmap: Requirements, Deadlines & Compliance H2 Compliance.

Building on that introduction, this article explains who could use Grandfathering or DUINs, the transitional provisions introduced to ease the change for GB-based companies, what these routes allowed companies to do, and why companies should still verify whether their UK REACH position remains valid today.

This information will be relevant to you if your company:

• Manufactures chemicals in GB
• Imports chemicals into GB;
• Previously relied on EU REACH registrations;
• Is unsure whether UK REACH registrations, Grandfathering, or DUINs were completed for your company following Brexit.
• Is unsure if UK REACH impacts them.

Why This Matters

Under UK REACH, a company that manufactures or imports a chemical substance into GB at 1 tonne or more per calendar year requires a UK REACH registration, unless an exemption applies.

Registration applies to individual substances, not mixtures. Therefore, manufacturers should consider the annual tonnage of each substance they manufacture in GB, while importers of mixtures should consider the annual tonnage of each separate substance contained within the mixture.

As a first step, companies should assess their role in the supply chain, identify the substances they manufacture or import into GB, and their annual tonnages. This will help determine whether Grandfathering, a DUIN or a new UK REACH registration may be relevant.

When the UK left the EU, EU REACH registrations no longer automatically provided regulatory coverage for companies manufacturing or importing substances into GB. To maintain market access while avoiding immediate disruption to supply chains, transitional provisions were introduced under UK REACH based on a company’s position under EU REACH and whether it held or relied on an existing EU registration.

The two most important transitional provisions were:

• Grandfathering
• Downstream User Import Notifications (DUINs)

Grandfathering vs DUIN: What’s the Difference?

The simplest distinction is who held the EU REACH registration before Brexit:

• Grandfathering – Your company held the EU REACH registration itself.
• DUIN – Another company held the EU REACH registration, typically your supplier, and you relied on that registration as a Downstream User and/or Distributor

Grandfathering: For Existing EU REACH Registrants

Grandfathering was the transitional route for GB-based companies that held an EU REACH registration in their own name before 1 January 2021, the end of the Transition Period.

Eligible registrations were automatically recognised under UK REACH when the regime came into force. However, companies still needed to complete follow-up steps in the Comply with UK REACH service, the UK REACH IT service,  to claim and maintain the grandfathered registration.

Grandfathering did not automatically transfer the underlying EU REACH data package to HSE. Rather, it deferred the requirement to submit the full registration information package. In summary, grandfathering carried the registration, not the data. Therefore, the registrant must prepare the information required by the applicable UK REACH deadline. This depends on the substance, the annual tonnage and hazard profile. Further details regarding the deadlines are shown below.

Grandfathering was relevant to existing EU REACH registrants, rather than companies relying on another legal entity’s registration elsewhere in the supply chain.

Only Representative (OR) arrangements and legal entity transfers can affect whether Grandfathering may be possible, so these scenarios should be checked carefully. In these scenarios, it is advised to seek expert advice.

The original deadline for the initial Grandfathering steps was 30 April 2021, but late submissions for eligible registrations can still be made through the Comply with UK REACH service.

DUIN: For Former Downstream Users and Distributors Under EU REACH

A Downstream User Import Notification (DUIN) was designed for GB companies that, before Brexit, relied on an EU REACH registration held elsewhere in the supply chain rather than holding the registration themselves.

Eligible GB businesses could submit a DUIN to suspend their registration duty until the relevant registration deadline and avoid immediate supply chain disruption, A GB-based Only Representative could also submit a DUIN on behalf of the non-GB manufactures GB importers, so companies utilizing Only Representatives should confirm whether this was done and whether the arrangement covers their current supply chain.

The original DUIN deadline was 27 October 2021. However, late DUIN submissions are still possible in certain circumstances, and eligibility should be assessed case by case.

Who Is Eligible for a DUIN?

DUIN eligibility depends on whether the business was an existing GB downstream user or distributor under EU REACH before Brexit, and whether the substance qualifies as a protected transitional import.

To be eligible for the DUIN the import must be a ‘protected transitional import’, this  applies where companies were a GB downstream user or distributor under EU REACH during the two years before the end of the Transition Period i.e., between 1 January 2019and 31 December 2020 companies must have imported or used the relevant EU REACH-registered substance into GB during that period.

Key eligibility criteria include:

• The imported substance(s) must have been imported from the EU and be covered by an existing EU REACH registration by the EU manufacturer/importer or;
• If the import was from outside the EU it was being covered by an EU-based Only Representative (OR).
• The use/import in GB must have occurred in the two years leading up to the end of the transition period (i.e., from 1 January 2019 to 31 December 2020 inclusive).

Where the relevant criteria are met, businesses can rely on the DUIN route and benefit from extended UK REACH registration deadlines.

A DUIN does not permanently replace registration. Instead, it postpones the registration obligation until the relevant phased UK REACH deadline.

UK REACH Registration Deadlines:

DUINs Are the First Step, Not the Final Step

Although the phased UK REACH registration deadlines may still seem some way off, companies should review their position now. A DUIN delays the registration obligation, but it does not remove it. Companies should confirm whether their DUINs still reflect current suppliers, sourcing routes, legal entities, import volumes and any Only Representative arrangements. Where circumstances have changed, it is possible the DUIN route may no longer be applicable.

Where a full UK REACH registration will be required, companies should begin considering data access, supplier support and internal information needs, well ahead of the relevant deadline. This will be explored further in a future article.

What If Neither Applies?

If neither Grandfathering, a DUIN nor another transitional route applies, a new UK REACH registration may be required before manufacture, or imports reach 1 tonne per year.

The process begins with an Article 26 Inquiry, followed by submission of a registration dossier through the UK REACH system.

Though, if the substance has been registered under EU REACH, another route may be available: New Registration of an Existing Substance (NRES), which will be covered in our next article.

Key Questions

If your company imports or manufactures substances in GB, ask:

1. Are we manufacturing or importing any substances into GB at 1 tonne or more per year?
2. Do we hold a UK REACH registration, Grandfathered registration or DUIN, or are we covered by an Only Representative?
3. Have our suppliers, legal entities, sourcing routes, volumes or supply chains changed since Brexit?
4. Which UK REACH registration deadline applies to our substance(s)?
5. If an Only Representative submitted a DUIN for us, does that arrangement still apply?

If you are unsure, H2 Compliance can help assess your substance portfolio and identify any next steps.

Key Takeaways

• Grandfathering applies to companies that already held an EU REACH registration in their own name.
• DUINs applies to companies that relied on another company’s EU REACH registration, including registrations held by suppliers or Only Representatives.
• Both mechanisms help businesses maintain GB market access after Brexit.
• A DUIN delays registration but does not permanently replace it.
• Changes to suppliers, legal entities, sourcing routes or import volumes can affect compliance.

For support assessing your UK REACH position, please contact H2 Compliance.

Next in the UK REACH Roadmap: Article 26 Inquiries and NRES Registrations – Follow us on LinkedIn to stay up to date with our latest articles.

For any assistance with compliance with UK REACH please feel free to contact us.

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Published October 13th, 2026

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