What is the '100 percent' identity testing rule under 21 CFR Part 111?

What the regulation actually says

21 CFR 111.75(a) sets out what a manufacturer must do before using a component. The identity-testing requirement is at 111.75(a)(1)(i): a manufacturer must “conduct at least one appropriate test or examination to verify the identity of any component that is a dietary ingredient, unless you petition the agency under paragraph (a)(1)(ii) of this section and the agency exempts you from such testing.” That is the rule practitioners shorthand as “100 percent identity testing”: not because it requires 100 percent of anything numeric, but because, absent a granted exemption, there is no sampling plan: every lot gets tested.

This sits inside a larger obligation. Before use, a manufacturer must also, under 111.75(a)(2), “confirm the identity of other components and determine whether other applicable component specifications… are met,” either by testing or by relying on a qualified supplier's certificate of analysis. Identity of a dietary ingredient and everything else are treated differently by design, and the rule singles out dietary-ingredient identity for its own, stricter provision.

The petition route: the only way out

21 CFR 111.75(a)(1)(ii) describes the sole exception: a manufacturer “may submit a petition, under 21 CFR 10.30, to request an exemption from the testing requirements… The petition must set forth the scientific rationale, and must be accompanied by the supporting data and information, for proposed alternative testing that will demonstrate that there is no material diminution of assurance, compared to the assurance provided by 100 percent identity testing, of the identity of the dietary ingredient before use when the dietary ingredient is obtained from one or more suppliers identified in the petition.” If FDA grants it, testing then proceeds “under the terms specified by FDA when the petition is granted”. Reduced testing is not a default a manufacturer can adopt on its own judgment.

In practice this means: no petition on file, no reduced schedule. A manufacturer that tells you it “doesn't need to test every lot” for a given ingredient should be able to produce the FDA-granted petition and its terms. Absent that, the regulation defaults to testing every lot.

Identity vs. everything else: a different bar

The distinction matters because the two provisions read almost alike but aren't. Reliance on a supplier's certificate of analysis is expressly permitted for non-identity specifications (purity, strength, composition, and contaminant limits) under 111.75(a)(2)(ii), subject to first qualifying the supplier by confirming the reliability of their test results, documenting how the supplier was qualified, periodically re-confirming the certificate, and having quality control review and approve the qualification. Identity of a dietary ingredient carries no such CoA-reliance path under 111.75(a)(1): it requires the manufacturer's own test or examination.

The gap this closes shows up in FDA's enforcement record. In a warning letter to a supplement manufacturer, FDA stated directly: “21 CFR 111.75(a)(2) does not allow firms to rely on a certificate of analysis to confirm the identity of a dietary ingredient. Rather, under 21 CFR 111.75(a)(1)(i), you must conduct at least one appropriate test or examination to verify the identity of any component that is a dietary ingredient, prior to using a component (or submit an exemption petition under 21 CFR 111.75(a)(2)(ii)).” That letter cited a firm relying on supplier CoAs for identity in place of its own testing, precisely the substitution the rule does not permit.

What it means for a brand that doesn't manufacture

The testing obligation under 111.75 runs to whoever manufactures the dietary supplement, typically your contract manufacturer, not you. But that does not make it someone else's problem to verify. FDA's own guidance on Part 111 states that a brand distributing a product under its own label “has an obligation to know what and how manufacturing activities are performed so that… [it] can make decisions related to whether… products conform to established specifications”: a duty that cannot be contracted away by outsourcing the manufacturing.

1. Ask which method your manufacturer uses for identity testing on each dietary ingredient in your formula, and whether it's applied per lot.
2. If they say a reduced schedule applies to any ingredient, ask for the FDA-granted petition under 111.75(a)(1)(ii) and its stated terms, not a supplier CoA and not a verbal assurance.
3. Confirm the test result is tied to the specific lot number used in your batch, not a generic specification sheet for the ingredient in the abstract.
4. Where a numeric identity or purity limit matters for your product type, check the current citation in the requirements library rather than assuming a number. See /requirements/fda_111/all-product-types.

• Never say a document 'proves' compliance. A lot-specific identity test result is evidence a reviewer looks for, not a verdict.
• A manufacturer's general cGMP certification does not, on its own, show identity testing happened on your specific lots.

Related: 21 CFR Part 111 explained for brand owners, how to read a Certificate of Analysis, and what your contract manufacturer is responsible for. The free check shows which documents are on file for a SKU; it does not perform identity testing on your behalf.