Importers of HS 3920.20 (of polymers of propylene) from Mexico actually paid 7.67% on the taxed portion of the value in 2026-06 — 0.01% across everything shipped, taxed or not. Measured from official duty receipts, not the rulebook: the statutory MFN base rate on this code is 4.2%. Over the window the rate on the taxed portion moved 4.2% → 7.67%, with the largest single step +15.6pp in 2025-04. Measured from official US duty receipts · as-of 2026-06 · confidence: measured, not modelled. The HTS base rate is 4.2% — importers actually paid 7.67%, so the trade-war overlay added 3.5 pts, measured at the border (not a summed rulebook estimate). Reproduce exactly: tariff_story(hs: "3920.20", origin: "Mexico") · see it at trimtabist.com/tariffs
HS 3920.20. The schedule base rate is 4.2%; importers from Mexico actually paid 7.67% on the dutiable value in 2026-06 — the trade-war overlay added 3.5 points, measured at the border. Measured, not modelled.
Over the window the collected rate moved 4.2% (2023-07) → 7.67% (2026-06), largest single step +15.6pp in 2025-04.
5 Chapter-99 measures name Mexico; scope mapping is partial (several annexes are PDFs) — absence never means exemption. They do not sum, and some are product-specific — the collected rate above is the composed truth.
All goods from Mexico · the whole tariff ledger · 1 CBP ruling cite this code · reproduce: tariff_story(hs: "3920.20", origin: "Mexico") via /connect. Not customs or legal advice.