Importers of HS 3923.21 (of polymers of ethylene) from Thailand actually paid 12.61% on the taxed portion of the value in 2026-06 — 12.58% across everything shipped, taxed or not. Measured from official duty receipts, not the rulebook: the statutory MFN base rate on this code is 3%. Over the window the rate on the taxed portion moved 3% → 12.61%, with the largest single step +5.2pp in 2025-09. Measured from official US duty receipts · as-of 2026-06 · confidence: measured, not modelled. The HTS base rate is 3% — importers actually paid 12.61%, so the trade-war overlay added 9.6 pts, measured at the border (not a summed rulebook estimate). Reproduce exactly: tariff_story(hs: "3923.21", origin: "Thailand") · see it at trimtabist.com/tariffs
HS 3923.21. The schedule base rate is 3%; importers from Thailand actually paid 12.61% on the dutiable value in 2026-06 — the trade-war overlay added 9.6 points, measured at the border. Measured, not modelled.
Over the window the collected rate moved 3% (2023-07) → 12.61% (2026-06), largest single step +5.2pp in 2025-09.
Thailand's lower duty (12.58% vs 18.78%) lets it price up to 5.5% above China at the factory and still match on duty-inclusive customs cost. But on the LATEST measured prices, China actually lands cheaper — $1.67/kg vs $2.04/kg (duty in, freight out).
All goods from Thailand · the whole tariff ledger · 2 CBP rulings cite this code · reproduce: tariff_story(hs: "3923.21", origin: "Thailand") via /connect. Not customs or legal advice.