3 Key Insights from CBP’s New Isotopic Testing Guidance for UFLPA Compliance [2026 update]

Updated November 5, 2026

On November 12, 2024, U.S. Customs and Border Protection (CBP) released its first detailed guidance on isotopic testing, outlining a science-based approach to verifying the geographic origin of materials under the Uyghur Forced Labor Prevention Act (UFLPA). CBP shared recommendations for choosing reliable testing providers and encourages importers to test early as part of their due diligence program.

In June 2026, CBP followed up with its Forced Labor Enforcement Operational Guidance for Importers. According to Holland & Knight, it replaces the 2022 UFLPA-only guidance and confirms that CBP may use isotopic testing to assess origin claims.

Here are three key insights from the CBP recommendations and what they mean for your business.

1. Isotopic testing is key to verifying material origins for UFLPA compliance

With the regulation in effect since June 2022, UFLPA compliance and supply chain traceability has been a critical element of importers’ due diligence efforts. The Act allows CBP to detain goods presumed to be made with forced labor from entering the United States.

The new CBP guidance highlights isotopic testing as a critical tool for determining the geographic origin of materials, particularly high-risk commodities like cotton.

“Isotopic testing is a scientific method that identifies the atomic structure of naturally occurring materials, or a “fingerprint” of the material, affected by local environmental conditions. For example, in the case of cotton, it is the environmental conditions experienced by the plant during growth, not the seed’s origin, that will determine the isotopic fingerprint of the cotton fiber. When that fingerprint is compared to a library of like materials from various geographic areas, the test can determine that the raw material is consistent with the claimed geographic origin.”

- CBP Guidance Document

2. CBP encourages private sector testing

CBP has tripled its isotopic testing capabilities in recent years, but their testing is more focused on identifying risks, which means importers are still responsible for conducting due diligence to monitor their supply chains.

According to the Federal Register, the UFLPA Entity List reached 187 entities in August 2026. CBP encourages importers to take a proactive role by engaging private sector testing providers.

If your documents aren't enough to secure release of a detained shipment, CBP may issue a CF-28 requesting a product sample for isotopic testing. Building traceability that stands up to enforcement matters because a detained shipment can take up to four months to release. In textiles, that means a lost season.

Testing before shipment means you already have that evidence. This can support a more proactive compliance strategy for brands and retailers.

“Even with these additional investments, CBP will have limited testing resources and does not have the capacity to test all U.S. imports. This is why CBP continues to encourage the inclusion of private sector testing in importer due diligence programs to help identify and manage risk.”

- CBP Guidance Document

3. Choosing a provider that meets CBP isotopic testing standards matters

According to CBP, importers should look for providers with scientific expertise, advanced equipment, and trained experts required for isotopic testing and interpretation. Some of the key standards include:

• Chain of custody: Isotopic testing providers must document the handling of samples, from receipt of the sample through disposition.
• Reference library: Providers should have access to a statistically robust library with known-provenance samples from all commercially relevant growing regions.
• Statistical modeling: Providers must use advanced models to interpret isotopic data and determine geographic origins.
• Accreditation: Laboratories should meet ISO/IEC 17025 standards and participate in proficiency testing.

“The test provider should have a statistically significant number of materials in its in-house reference library in order to confidently verify origin. Materials in the reference library should have known provenance and should represent all commercially relevant growing regions being tested.”

- CBP Guidance Document

How to choose a UFLPA isotopic testing lab

CBP’s guidance makes one thing clear: isotopic test results only help if they come from a provider whose methods will hold up when CBP reviews them. Before you commission testing, check each provider against the standards CBP has set out. Below, each criterion is paired with the questions to ask a lab and how Oritain meets it.

Frequently asked questions

What is CBP’s isotopic testing guidance?

CBP issued its first detailed guidance on isotopic testing on November 12, 2024. It describes isotopic testing as “a critical tool for determining the geographic origin of materials,” especially cotton, and sets out a science-based way to verify origin under the UFLPA. It also urges importers to test early as part of their due diligence and recommends what to look for in a testing provider.

Does CBP accept private sector isotopic testing?

Yes. CBP actively encourages it. CBP has tripled its own isotopic testing capacity in recent years, but it can’t test every US import, and its own testing focuses on identifying risk. Importers remain responsible for their supply chains, and CBP sees private sector testing as a key part of their due diligence.

What should importers look for in a UFLPA testing lab?

CBP’s guidance points to four standards. The lab should document chain of custody from receipt to disposal. It should hold a statistically robust reference library of known-origin samples covering all relevant growing regions, and use advanced statistical models to determine origin. It should also be accredited to ISO/IEC 17025 and take part in proficiency testing. The provider also needs the right scientific expertise, equipment and trained specialists.