Fiber Blend HS Code Classification: The 50/50 Problem Explained
A 51% cotton / 49% polyester garment and a 50% cotton / 50% polyester garment can land in different tariff chapters with different duty rates. The rule governing this is Section XI, Note 2(A) of the Harmonized System — a specific, legally binding Section Note, not the general "essential character" test many guides point to. Note 2(A) doesn't require a 50% majority: a fiber only has to outweigh each other single fiber individually. A real, published CBP ruling on a 50/50 cotton-polyester T-shirt shows exactly how this plays out, including the duty difference.
Compiled and reviewed by Chowdhury Remon, Founder & CEO — 27+ years in garment manufacturing · Last verified July 2026 against HTSUS and WCO HS 2022 nomenclature
The Legal Framework: GRI, and Where Section XI Note 2 Fits
Every HS classification in every country follows the same six General Rules of Interpretation (GRI), published by the World Customs Organization, applied in order. GRI 1 says classification starts with the heading wording and any relevant Section or Chapter Notes — and for textiles, that reference matters enormously, because Section XI (which covers Chapters 50–63, essentially all textiles and apparel) has its own Note 2 that specifically governs fiber mixtures. This Note is applied before general concepts like "essential character" ever come into play for a simple fiber blend.
| Rule | What It Does |
|---|---|
| GRI 1 | Classify by the heading's plain wording plus Section/Chapter Notes. For textiles, this is where Section XI Note 2 gets pulled in. |
| GRI 2(a) / 2(b) | Covers incomplete/unassembled goods (2a) and mixtures of materials generally (2b) — but 2(b) explicitly defers to GRI 3 when a more specific rule (like Section XI Note 2) doesn't already resolve it. |
| GRI 3(a) | When two headings could both apply, the more specific description wins over a general one. |
| GRI 3(b) | Essential character — for genuinely composite goods (mixed materials, sets, multi-component items) where no more specific rule applies. For plain fiber blends, Section XI Note 2 usually resolves classification before this is ever needed. |
| GRI 3(c) | If neither 3(a) nor 3(b) resolves it, use the heading that occurs last in numerical order among those equally in contention. Section XI Note 2(A) borrows this exact tie-break logic for fiber ties. |
| GRI 4, 5, 6 | Rare fallback (4), packaging (5), and applying the same logic one level deeper at the subheading (6). |
Section XI Note 2(A), in Its Actual Wording
This is the operative rule, quoted directly from the WCO's Harmonized System nomenclature: goods made of a mixture of textile materials "are to be classified as if consisting wholly of that one textile material which predominates by weight over any other single textile material." Only "when no one textile material predominates by weight" does the tie-break apply: classify under whichever heading "occurs last in numerical order among those which equally merit consideration."
Read that carefully — it says predominates over any other single material, not over 50% of the total blend. That distinction is exactly what makes tri-blends and quad-blends resolvable without ever reaching a vague "essential character" judgment call in most cases.
Working Through a Tri-Blend Correctly
Take a 40% polyester / 35% cotton / 25% rayon fabric. No fiber reaches 50% of the total. But that's not the test. The test is: does any fiber beat each of the others individually? Polyester at 40% beats cotton's 35%, and it beats rayon's 25%. Polyester predominates over every other single fiber, so under Note 2(A) the fabric is classified as a man-made fiber (polyester) product — full stop, no essential-character analysis needed.
A genuine tie only happens when two fibers are exactly equal and both exceed everything else — for example 45% cotton / 45% polyester / 10% elastane. That's the specific, narrow case where the "last in numerical order" tie-break in Note 2(A) actually gets used.
Try It — Blend Classification Checker
Enter up to three fibers and their percentages to see which fiber predominates under Section XI Note 2(A), or whether you're in a genuine tie. This applies the predominance rule only — it doesn't account for construction (knit vs woven), garment type, gender, or country-specific subheadings, all of which also affect the final code.
This tool applies Section XI Note 2(A) predominance logic only. Confirm your final 6-to-10-digit code with a customs broker or an official binding ruling before relying on it for a shipment.
A Real Ruling: The 50/50 T-Shirt
US Customs and Border Protection ruling N237247 is a published, public example of exactly this scenario. A women's T-shirt made from a 50% cotton / 50% polyester blend was classified under HTSUS 6109.90.1090 (T-shirts of man-made fibers) — not the cotton heading — specifically because Section XI Note 2(A) and its Subheading Note 2(A) require the tie to be broken by whichever qualifying heading comes last in numerical order, and the man-made fiber subheading numerically follows the cotton one.
| Composition | HTSUS Heading | US Duty Rate |
|---|---|---|
| 100% cotton T-shirt | 6109.10.00 | 16.5% |
| 50% cotton / 50% polyester T-shirt (per N237247) | 6109.90.1090 | 32% |
Nearly double the duty rate, from what most people would consider a minor fabric formulation change. These are general (MFN) rates; country-specific programs and additional duty layers can change the final number further, which is exactly why the base classification has to be right before anything else is calculated.
How Customs Labs Actually Weigh Fiber Content
Customs labs don't weigh fabric "as received." They dry the sample to a constant oven-dry mass, then add back a standardized moisture regain allowance specific to each fiber — because different fibers naturally hold different amounts of moisture, and comparing raw as-received weights would unfairly favor high-moisture fibers. Cotton's official regain is 8.5%; polyester's is just 0.4%. Standard test methods for this are ASTM D1909 and ASTM D2495 internationally, and ASTM D629 or ISO 1833 for the fiber-identification and quantitative-analysis side.
This matters practically: a factory's own scale weight and a customs lab's conditioned weight can differ by a percentage point or two purely from this adjustment — which is exactly the margin that decides a genuinely close blend. Ask your fabric mill for lab results reported on this conditioned basis, not just raw greige weight, if your blend is close to a tie.
Trims, Elastane, and What Actually Counts in the Weight
The predominance calculation is based on the fabric of the garment itself, not separately-attached components like buttons, zippers, or non-textile trims, which are classified in their own right. Small amounts of elastane or spandex (commonly 2-5% for stretch) do count in the fiber-weight calculation, but at that level they rarely predominate over the main fibers on their own — the exception is a genuinely close primary blend where that extra percentage is enough to tip a near-tie.
Also worth knowing: construction matters as much as fiber. The same blend ratio can land in an entirely different chapter depending on whether the fabric is knit or woven — Chapters 61 (knitted) and 62 (woven) are structured in parallel but are legally separate chapters, so a fiber-content answer for one doesn't carry over to the other.
Trade Names Don't Determine Classification
Customs classifies based on actual fiber type, not marketing terminology. Lycra and Spandex are both classified as elastane. Lurex is treated as a metallic fiber. Most "bamboo" fabric is, chemically, a regenerated cellulosic fiber and is classified as rayon/viscose, not as a distinct bamboo category, regardless of hangtag language.
A few more common ones worth translating correctly before classification: Modal and Tencel/Lyocell are both regenerated cellulosic fibers, classified alongside viscose/rayon. Cupro is also a cellulosic fiber, chemically distinct from cotton despite sometimes being marketed alongside it. Acetate is its own distinct classification, not lumped with rayon. Nylon 6 and Nylon 6,6 are chemically different polyamides but are classified identically as nylon for HS purposes. Recycled polyester (rPET) is classified the same as virgin polyester — the tariff schedule doesn't distinguish recycled from virgin content.
If your spec sheet or a supplier's documentation uses a brand or trade name, translate it to the actual fiber category before classification, and keep that translation documented.
Why Country-Specific Codes Add Another Layer
The 6-digit HS code from Section XI Note 2(A) is internationally standardized, but the 8-to-10-digit extension that determines the exact duty rate is set by each importing country — US HTSUS uses 10 digits, EU's Combined Nomenclature (CN) uses 8, and each maintains its own statistical and duty detail beyond the shared 6-digit base. A correct 6-digit answer is the necessary first step, not the final one.
Preferential trade programs add a further layer: eligibility for reduced or duty-free treatment under programs like GSP, USMCA, or the EU's EBA/GSP schemes often has its own fiber-origin and processing rules, separate from the base classification question covered here. Don't assume a program you qualify for on one blend automatically applies once the fiber ratio changes.
What to Do When a Blend Is Genuinely Close
Get third-party fiber-content lab testing (ASTM D629 or ISO 1833) before bulk production, reported on the standard conditioned-weight basis, not raw greige weight. It's inexpensive relative to the cost of a reclassification, and gives you documented proof of composition.
For genuinely close or high-value shipments, request a binding ruling before you ship, not after a customs question arises. In the US this is CBP's eRulings system; the EU offers Binding Tariff Information (BTI); the UK offers an Advance Tariff Ruling (ATaR); Canada and Australia offer equivalent advance ruling programs through their own customs authorities. All are free and typically take 30-90 days, and the result legally protects that specific classification as long as your product matches what was described in the request.
Before filing a new request, search the destination country's public rulings database — CBP's CROSS system (where N237247, cited above, is publicly available) is the US example — since a near-identical product may already have a published ruling that settles the question without the wait.
Fiber Blend Classification FAQ
Section XI Note 2(A) doesn't actually require 50%. A fiber only has to predominate by weight over each other single fiber individually. A 40% polyester / 35% cotton / 25% rayon fabric is classified as polyester, because 40 beats 35 and 40 beats 25, even though polyester is nowhere near a majority of the total. A genuine tie only happens when two or more fibers are exactly equal and both beat everything else, and that's rare in practice.
Section XI Note 2(A) resolves it with a fixed, mechanical rule: classify under whichever heading occurs last in numerical order among the headings that equally merit consideration. This isn't a judgment call about which fiber "feels" more important, it's a numbering tie-break. A real CBP ruling (N237247) applied exactly this to a 50/50 cotton-polyester T-shirt and classified it under the man-made fiber heading, which numerically follows the cotton heading.
The care label is a starting reference, not the legal basis for classification. Customs labs measure fiber weight as oven-dry mass plus an official moisture regain allowance specific to each fiber (cotton 8.5%, polyester 0.4%), not simply "as received" weight. If a lab result differs meaningfully from the label or invoice, the lab result overrides the paperwork.
Usually not on its own. A 2-5% elastane content is normally too small to predominate over the main fibers under Section XI Note 2(A), so it typically doesn't shift the chapter by itself. But it does still count in the total fiber-weight calculation, and combined with a close cotton/polyester split it can occasionally tip a genuinely borderline blend. Report it accurately rather than rounding it out of the declared composition.
Yes, and a published CBP ruling shows exactly this: a 100% cotton T-shirt (6109.10.00) carries a 16.5% duty rate, while the same style at a 50/50 cotton-polyester blend (6109.90.1090) carries 32%, nearly double, from a fabric change most people would consider a small formulation tweak.
No. HS classification is based on fiber type (polyester, cotton, nylon, and so on), not on whether that fiber is virgin or recycled. Recycled polyester is still classified as polyester. Recycled content can matter for other things, like sustainability claims or certain trade-preference programs, but it doesn't change the tariff heading on its own.
For any blend where the split is close, yes. A third-party fiber-content lab test (ASTM D629 or ISO 1833 are the standard methods) is inexpensive relative to the cost of a customs reclassification, back-duty demand, or shipment delay, and it gives you documented evidence of composition if a customs authority later questions your declared classification.
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