Registered claim: decomposing the 2017-06 → 2025-05 rise in China’s effective burden into a rate effect (rates rise, 2017 duty-free coverage held fixed) and a coverage effect (formerly duty-free value taxed at end rates), the coverage term accounts for the larger share. Known before the run: the dutiable share moved roughly 42% → 93%; the split itself had not been computed.
What the record shows
In June 2017, 41.8% of Chinese import value paid any duty at all; the majority
entered free. The 2018–19 lists lifted that to ~60% and there it sat for six years. The
2025 wave took it to 91.3% — and the decomposition rules the story: of the
+45.2-point rise in the overall burden (2.71% → 47.92%), 25.98 points — 57.5%
— came from taxing what had been exempt, and 19.24 points from raising rates on
goods already taxed. The least-reported half of the tariff story is not a rate; it is the
end of the free lane. Since the 2026 retreat began the share has eased to 80.9% — still
double 2017.
Share of Chinese import value that paid any duty at all, monthly. 41.8% (2017-06) → 63.9% (2018-12) → 91.3% (2025-05) → 80.9% (2026-06). Source: TT-010 duty receipts.
What would prove this wrong
Registered falsifier: the rate effect alone, at 2017 coverage, explaining half or more of the burden rise. Measured: 42.5%. Not met.
Cite this
In print: “The 2025 wave didn’t just raise rates — it ended the exemptions” — a pre-registered event study
by the Trimtab US Trade Ledger, ruled 2026-08-06, from US Census port records and 174,440 vessel
stays (NOAA AIS, 2018–2024) — trimtabist.com/atlas/china-coverage-collapse For the record: Event Atlas · china-coverage-collapse · CONFIRMED · ruled 2026-08-06
This study is a frozen artifact: the ruling and its exhibits do not change when new
data lands. If the verdict is ever revised, the revision is printed here with its reason, and the
original stays on the record.