# Sources

Every number comes from officially published data, and each page states the version and the date it was checked. Every build checks the data, and nothing is published if a check fails.

## Data by tool

- Data: US International Trade Commission Harmonized Tariff Schedule, chapters 61, 62, 63, 65 and 99 and heading 4202; CBP MPF and HMF rates
- Version: HTS 2026 Revision 21; fees from 2026-10-01
- Checks: Every code exists in the official schedule; each code is on at most one active Section 301 China list and not in the four-year-review increases; each origin has exactly one additional-duty heading; no code appears in any exemption list

### Landed Cost and Profit per Unit Calculator

- Data: ECB euro reference rates (USD, CNY); duty as in the duty calculator; MPF and HMF as above
- Version: ECB 2026-10-21
- Checks: Rates downloaded at each build; duty worked out from the selected code; the worked example is computed at build time and in the page, and they must match

### Break-even ROAS and ACoS Calculator

- Data: Formulas: ROAS and ACoS as defined by Amazon Ads and Google Ads Help; costs entered by the user
- Version: —
- Checks: The table and worked example are computed at build time and in the page, and they must match

## Original sources

- USITC Harmonized Tariff Schedule: https://hts.usitc.gov/
- HTS chapter 99, U.S. notes 20 and 52: https://hts.usitc.gov/reststop/file?release=currentRelease&filename=Chapter%2099
- Customs user fees, effective 2026-10-01 (STR): https://www.strtrade.com/trade-news-resources/str-trade-report/trade-report/august/customs-user-fees-to-increase
- Supreme Court IEEPA ruling, 2026-02-20 (Norton Rose Fulbright): https://www.nortonrosefulbright.com/en-us/knowledge/publications/20f2de87/potential-refunds-us-supreme-court-overturns-ieepa-tariffs

All results are estimates, not rulings by customs or any platform. Confirm with a customs broker or the relevant authority before you import or quote.