Does FDA require testing of every single lot?

Not literally every one. 21 CFR 111.75(c) lets a manufacturer verify finished-batch product specifications through a sound statistical sampling plan applied across a subset of batches, or test every batch. The manufacturer chooses, and must document why the plan it picked gives assurance the specifications are being met.

If sampling is allowed, why do I need a COA for the specific lot I'm selling?

Because a Certificate of Analysis is a per-lot document by construction: its sample-identification section ties it to one batch. A sampling plan tells you which batches were directly tested; it doesn't retroactively produce a COA for a lot that wasn't one of them. For review purposes, the lot on sale needs its own matching document.

Can a supplier's certificate of analysis substitute for my manufacturer's own testing?

For components, yes, under conditions: 21 CFR 111.75(a)(2)(ii) allows relying on a supplier's COA if the manufacturer first qualifies the supplier by confirming the supplier's results, the COA states the method and limits used, and the supplier is periodically re-confirmed. This applies to incoming components, not to the finished product's own release testing.

What happens if a lot has no COA at all?

A reviewer has nothing to check that lot against, which is the strictest possible outcome, since there's no distinction from a lot that failed. Practically this means treating an untested lot as unverifiable for sale on a platform that requires evidence, not as a lot that's presumed fine.

How do brands with many active lots keep every one covered?

Request a COA from the manufacturer with every new lot rather than periodically, track the certificate date per lot rather than per product, and watch the document-age window (the strictest reported figure is 182 days) per lot rather than assuming last quarter's COA still covers this quarter's stock.

Guide

Do I need a Certificate of Analysis for every lot, or just the product?

By Jake, founder · Published 2026-08-17 · Updated 2026-08-17

A Certificate of Analysis covers one lot: results from one lot carry no authority for another. Separately, 21 CFR Part 111 lets a manufacturer verify finished-batch specifications through a sound statistical sampling plan rather than testing every batch. Together: not every batch is necessarily tested, but whichever lot is on sale needs its own current, matching COA.

Two different questions, easy to conflate

"Do I need a COA for every lot" is really two separate questions. The first is a manufacturing question: does Part 111 require the manufacturer to test every single batch before release? The second is a documentation question: for the lot currently on sale, does a reviewer need a document that specifically covers it? The answers are different (no to the first in most cases, yes to the second in every case) and conflating them is where brands get the wrong end of the requirement.

What Part 111 actually says about finished-batch testing

21 CFR 111.75(c), the operative text, reads: for "a subset of finished dietary supplement batches that you identify through a sound statistical sampling plan (or for every finished batch)," the manufacturer must verify that the batch meets product specifications for identity, purity, strength, and composition, and for contamination limits. The parenthetical matters: sampling a subset is explicitly permitted as an alternative to testing every batch. What the rule requires alongside the sampling choice is documentation: the manufacturer must record why the specifications it selected, tested through the sampling plan it chose, give assurance that the production system as a whole is meeting every product specification, and quality control personnel must review and approve that documentation.

Separately, §111.75(a)(2) covers incoming components rather than finished batches: a manufacturer may rely on a supplier's certificate of analysis instead of running its own test, but only after qualifying the supplier, which means confirming the supplier's own results, requiring the COA to state its method and limits, keeping records of the qualification, and periodically re-confirming it. That is a narrower, conditional allowance for components; it does not describe how finished-product testing works.

What 21 CFR 111 actually permits, by evidence type
Evidence	What Part 111 requires	Citation
Finished-batch specifications (identity, purity, strength, composition, contaminant limits)	Verify via a sound statistical sampling plan across a subset of batches, or test every batch. The manufacturer's documented choice.	21 CFR 111.75(c)
Component identity	At least one appropriate test or examination before use, for every component that is a dietary ingredient (no sampling allowance).	21 CFR 111.75(a)(1)
Other component specifications	Test directly, or rely on a qualified supplier's certificate of analysis under documented conditions.	21 CFR 111.75(a)(2)

Quoted and summarized from the current eCFR text of 21 CFR Part 111, Subpart E, fetched via the eCFR API. Read the section text itself for the operative language; this table is a map, not a substitute.

Why a COA is still a per-lot document regardless

A sampling plan governs what the manufacturer tests before release. It says nothing about what document exists for any one specific lot afterward. A Certificate of Analysis identifies the sample it covers (product name, lot or batch code, dates) and results from one lot carry no authority for a different lot of the same product, as covered in how to read a Certificate of Analysis. If a manufacturer's sampling plan tested lot 4 and released lots 5 through 9 on the strength of that plan without individually testing them, only lot 4 has a COA a reviewer can check. Lots 5 through 9 may be entirely sound product, and the sampling plan is exactly what Part 111 permits, but there is no lot-specific document to hand a TIC provider or a retailer for any of them unless the manufacturer also issues one.

This is the gap that causes real verification failures: not that the manufacturing was inadequate, but that the paperwork trail available to the brand does not reach the specific lot currently being sold.

What this means when you ask your manufacturer

Ask directly whether their sampling plan produces a COA for every lot, or only for the sampled ones. This is a documented policy under §111.75(c)(3), so a manufacturer with a real quality system can answer it precisely.
If only sampled lots get individually tested, ask what documentation exists for the unsampled lots. Some manufacturers issue a certificate of conformance tied to the sampling plan rather than a full COA; know which you're holding.
Request a COA with every lot shipped to you, not on request after the fact. A standing instruction is cheaper than chasing one down when a review is already underway.
Track the certificate you actually hold against the lot codes you actually have in inventory or on sale. A mismatch here is functionally the same as having no COA at all.

Keeping up with many active lots

Brands running several SKUs, each with lots turning over every few months, end up with more open COA obligations than a spreadsheet comfortably tracks. The practical approach:

File by lot, not by product. The newest lot's COA is the one that matters for a current review, and an old one under the same product name is not a substitute.
Know each SKU's current lot code and confirm the COA on file matches it, not just the product name.
Watch the document-age window per lot rather than per product family, since lots don't age out on the same calendar.
Run the free check: it reads certificate dates and lot identifiers off uploaded COAs and shows which current lots have matching, current documentation and which don't.

Related: how long a lot's COA stays usable for verification is covered in how long a COA is valid for Amazon, and what happens once it ages out is covered in what happens when a supplement COA expires. Numeric limits a lot's results are checked against live in the requirements library; Compliant Always does not set those limits; it reads a COA against them and shows what a reviewer would flag.

Sources

eCFR: 21 CFR 111.70 to 111.77 (specifications; determining compliance, including the statistical sampling allowance at §111.75(c)) accessed 2026-08-17
eCFR: 21 CFR Part 111, Subpart G (component, packaging, and received-product handling requirements) accessed 2026-08-17

Frequently asked questions

Does FDA require testing of every single lot?: Not literally every one. 21 CFR 111.75(c) lets a manufacturer verify finished-batch product specifications through a sound statistical sampling plan applied across a subset of batches, or test every batch. The manufacturer chooses, and must document why the plan it picked gives assurance the specifications are being met.
If sampling is allowed, why do I need a COA for the specific lot I'm selling?: Because a Certificate of Analysis is a per-lot document by construction: its sample-identification section ties it to one batch. A sampling plan tells you which batches were directly tested; it doesn't retroactively produce a COA for a lot that wasn't one of them. For review purposes, the lot on sale needs its own matching document.
Can a supplier's certificate of analysis substitute for my manufacturer's own testing?: For components, yes, under conditions: 21 CFR 111.75(a)(2)(ii) allows relying on a supplier's COA if the manufacturer first qualifies the supplier by confirming the supplier's results, the COA states the method and limits used, and the supplier is periodically re-confirmed. This applies to incoming components, not to the finished product's own release testing.
What happens if a lot has no COA at all?: A reviewer has nothing to check that lot against, which is the strictest possible outcome, since there's no distinction from a lot that failed. Practically this means treating an untested lot as unverifiable for sale on a platform that requires evidence, not as a lot that's presumed fine.
How do brands with many active lots keep every one covered?: Request a COA from the manufacturer with every new lot rather than periodically, track the certificate date per lot rather than per product, and watch the document-age window (the strictest reported figure is 182 days) per lot rather than assuming last quarter's COA still covers this quarter's stock.