Importers of HS 8419.50 (brazed aluminum plate-fin heat exchangers) from Mexico actually paid 21.86% on the taxed portion of the value in 2026-06 — 11.38% 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% → 21.86%, with the largest single step +26.1pp in 2025-03. Measured from official US duty receipts · as-of 2026-06 · confidence: measured, not modelled. The HTS base rate is 4.2% — importers actually paid 21.86%, so the trade-war overlay added 17.7 pts, measured at the border (not a summed rulebook estimate). Reproduce exactly: tariff_story(hs: "8419.50", origin: "Mexico") · see it at trimtabist.com/tariffs
HS 8419.50. The schedule base rate is 4.2%; importers from Mexico actually paid 21.86% on the dutiable value in 2026-06 — the trade-war overlay added 17.7 points, measured at the border. Measured, not modelled.
Over the window the collected rate moved 4.2% (2023-07) → 21.86% (2026-06), largest single step +26.1pp in 2025-03.
Mexico's lower duty (11.38% vs 42.43%) lets it price up to 27.9% above China at the factory and still match on duty-inclusive customs cost. But on the LATEST measured prices, China actually lands cheaper — $12.56/kg vs $28.6/kg (duty in, freight out).
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 · 8 CBP rulings cite this code · reproduce: tariff_story(hs: "8419.50", origin: "Mexico") via /connect. Not customs or legal advice.