Methodology & data sources

Where every number comes from, what "last verified" means, and what this site will not do.

Last verified 06/12/2026

What we track and where it comes from

Every tariff measure on this site is hand-curated from primary sources: the Federal Register (executive orders, proclamations, agency notices), USTR actions, CBP guidance, and court documents. Each record links to the documents it is based on — if we can't cite it, we don't publish it.

Signal strength: a post is not a law

In the current policy environment, tariffs are announced on social media long before — and sometimes without ever — becoming law. Every measure and timeline event carries a signal-strength label so you can see instantly whether something is a verbal threat, a signed order, a published Federal Register notice, active CBP guidance, or a final court ruling. Our feed separates formal compliance changes from threat-watch items for the same reason: repricing your supply chain on a headline is expensive.

Statement only

Verbal remark or social media post — no legal instrument exists and no compliance action is required.

Executive order

A signed executive order or proclamation exists.

Federal Register

Published in the Federal Register — formally part of U.S. law.

CBP guidance

CBP has issued implementation instructions — duties are being collected at the border.

Court ruling / statute

Settled by statute or a final court ruling.

What "last verified" means

Each measure shows the date a human last checked the record against its primary sources. Measures change fast; if a record's verification date looks old relative to the news, treat the official sources as authoritative. Our build process refuses to publish measures without citations and warns on records older than 120 days.

Update cadence

The measure dataset is updated with each site release, typically multiple times per week during active policy periods. The policy tracker additionally pulls live Federal Register documents daily.

Limitations — read this

This site summarizes complex legal instruments; summaries are not a substitute for the documents themselves. Duty rates shown in the HTS reference are a curated snapshot, not a live USITC feed. Antidumping/countervailing duties, quota mechanics, and entry-specific factors (valuation, origin, exclusions) can change what you actually pay. Always verify against official sources before making decisions: the Federal Register, the USITC HTS, CBP CSMS messages, and a licensed customs broker or trade attorney for anything binding.