Two logos turn up on almost every uniform quotation that crosses my desk: GOTS and OEKO-TEX. They are usually listed side by side, as though they were two spellings of the same reassurance. They are not. They audit different things, at different points in the chain, and a garment can carry one while failing entirely at what the other covers.
The shortest version I can give a procurement committee is this. GOTS is about how it was made. OEKO-TEX STANDARD 100 is about what is in it at the end.
GOTS follows the chain, not the shirt
The Global Organic Textile Standard starts at the fibre and follows it forward. To carry the organic label a product needs at least 95 per cent certified organic fibre; the made with organic grade needs 70 per cent. But the fibre percentage is the least interesting part of it. GOTS also governs the processing: which chemical inputs may be used in dyeing and finishing, wastewater treatment at wet processing units, restrictions on inputs such as chlorine bleach and certain azo dyes, and a set of social criteria drawn from ILO conventions covering the facilities in scope.
The mechanism that makes it work is paperwork nobody outside the trade ever sees. Every certified operator holds a scope certificate listing exactly which processes and products it is certified for, and every shipment between certified operators carries a transaction certificate. That is what allows an auditor to check that the organic cotton leaving the gin is the same volume arriving at the spinner. When I verify a supplier's GOTS claim, the scope certificate is the document I ask for, never the logo. A mill being GOTS certified for jersey tells you nothing about the woven shirting the same mill is also quoting you.
OEKO-TEX tests the finished article
STANDARD 100 works the other way round, and ignores provenance completely. An article can be conventional polyester, grown and spun and dyed anywhere, and still certify, because the question being asked is whether the finished item tests below limit values for a long list of regulated and suspect substances. What matters most for school uniform is the product class. Class I covers articles for babies and toddlers up to three years and carries the strictest limits. Class II covers items with direct skin contact, which is where a school shirt or polo sits. A certificate is valid only for the specific article and the class it was tested in, and it runs for a year.
Both schemes revise. The 2026 update to the OEKO-TEX regulations became binding on 1 June, tightening limits on bisphenols and extending restrictions on fluorinated compounds, and GOTS is moving to version 8.0. A certificate issued under an older version is not fraudulent. It was simply tested against a shorter list, which is worth knowing when someone waves a certificate from four years ago.
Neither one covers everything
GOTS says little about residue levels in the finished garment for substances outside its own input list. OEKO-TEX says nothing about who farmed the cotton, what the dyehouse discharged, or who was standing at the sewing machine. OEKO-TEX has separate schemes for that, STeP for facilities and MADE IN GREEN for a traced article, and those are the ones to ask for if the labour question matters to you. For an institutional buyer it should.
Three things to check, none requiring expertise
Ask for the certificate number and look it up in the issuing body's public database, because a scanned PDF proves very little on its own. Check that the scope covers the article you are actually buying rather than a different product from the same factory. Check the expiry date against your delivery date, since both certificates are annual and a lot produced after expiry is not covered by it.
We link certificates at garment level for exactly this reason, with expiry tracked, because a certificate that lapsed in March does not describe a shirt made in June. It is a small piece of administrative discipline and it removes most of the ambiguity in this area.
The label soup is not a conspiracy. It is what happens when several honest schemes each answer one part of a question and nobody assembles the parts. That assembly is the buyer's job, and it is a shorter job than it looks.