The United States splits textile outerwear on a laboratory test, and the two halves are not close. A man-made-fibre jacket that passes it is classified “water resistant” at 7.1%; the otherwise identical jacket that does not is “other”, at 27.7%. That gap — 20.6 percentage points — is larger than the difference shipping makes, and larger than most people’s idea of what duty even is.
The test is specific. Additional U.S. Note 2 to Chapter 62 requires the garment to hold back water under a head pressure of 600 millimetres, letting no more than 1.0 gram through in two minutes — and the resistance has to be “the result of a rubber or plastics application to the outer shell, lining or inner lining”. In riding-gear terms that means a laminated or coated membrane: Gore-Tex, Drystar, D-Dry, H2Out, Sympatex, AbsoluteShell and their siblings.
What does not qualify is the interesting part. A durable-water-repellent finish sold as “water resistant” or “water repellent” is the failing side of that same test. A softshell is not a waterproof shell. And a removable waterproof liner is genuinely arguable rather than plainly qualifying — so when the answer is unclear we charge the higher rate, on the principle that an estimate should surprise you in your favour rather than at the door. If you are not sure which you have, leave the control on “not sure”: that is the conservative answer, not a missing one.
The same split runs through riding trousers. Heading 6203 for men’s and 6204 for women’s carry water-resistant trouser lines at 7.1% against 28.6% for “other” — a 21.5 percentage-point gap, on the same 600 mm test and the same Additional U.S. Note 2. Waterproof over-trousers and laminated adventure pants are exactly the garments it was written for. It does not reach base layers: a knit thermal top or bottom is a different chapter of the tariff altogether and never qualifies, whatever the name claims, so the calculator keeps it on its own rate.
Men’s and women’s garments carry identical rates on the water-resistant side of this split, so it is not a gender question. (On the “other” side the schedule does differ slightly for trousers — men’s 27.9%, women’s 28.6% — and we publish the higher of the pair, because we cannot know which one you are buying.) And it is a United States rule only — Canada, the EU, the UK and Australia do not distinguish waterproof from non-waterproof outerwear in their schedules, which is why the control disappears when you change destination.