How We Verify These Tariff Rates
Every tariff number on this site traces to an official source: the USITC tariff schedule, USTR, the Federal Register, or CBP. This page explains the checking ritual behind the "rates last verified" date, so you can judge for yourself whether to trust the numbers.
What does the "rates last verified" date mean?
It means a person re-checked the calculator's tariff and fee assumptions against official sources on that date. It's not a timestamp from a script: the date only moves after a real check completes.
Every stamp on the calculator shows the same date, and the whole site moves together when a check completes. Content pages additionally carry their own "last checked" date in the text, because an article's claims can be re-verified on a different day than the calculator's planning defaults.
What gets checked, and when?
The full check runs on a regular schedule, with extra checks in the run-up to known deadline dates (for example, a temporary tariff layer's scheduled expiry). Each pass covers every layer the calculator models:
- Base HTS duty context - the category planning estimates and the guidance to look up your exact code.
- Section 301 China tariffs - list status, rates, and any proposed actions.
- Section 232 trade-remedy duties - covered products and current rates.
- Temporary surcharges - anything with an expiry or court date attached gets tracked to that date, not just on the regular cycle.
- Customs fees - the MPF and HMF levels for the current fiscal year.
- De minimis status - whether low-value shipments still owe normal duty.
Every page on this site that makes dated tariff claims is on the review list. And pages with worked dollar examples get their numbers recomputed, not just their "last checked" date bumped.
Which sources count as official?
Everything here traces to these four sources, not to news coverage or AI summaries:
- The USITC Harmonized Tariff Schedule for product-level duty rates.
- USTR's Section 301 tariff actions for the China-specific lists and exclusions.
- The Federal Register for proclamations, fee notices, and suspension rules as legally published.
- U.S. Customs and Border Protection, including its CSMS messages, for how rules are actually collected at entry.
Secondary summaries can flag that something moved, and that's useful. But nothing on this site changes until the underlying official text confirms it: third-party summaries have gotten rates wrong before, and the dated content pages here link the specific official documents behind each claim.
What happens when a rate actually changes?
Three things, in the same update: the calculator's planning defaults change, every affected page gets its numbers (not just its dates) corrected, and the "rates last verified" stamp moves.
Then a one-line email goes out to the tariff change alerts list: what changed, who it affects, and a link to the official source. That email goes out after the verification, never before it.
If you catch a stale number before I do, email hello@importcostcalculator.com and I'll check it against the sources above.
Get a one-line email when tariffs change
One short, human-verified email per confirmed change: what changed, who it affects, and the official source. No newsletter, no spam.
What this process will not do
It will not auto-publish. Automation watches the sources and flags what moved, but a person confirms the change against the official text before any number here changes. A wrong tariff figure quietly shipped by a script is exactly the failure this ritual exists to prevent.
It also will not pretend to be a customs filing. Several of the calculator's values are deliberately conservative planning defaults, and the pages say so where it matters. The goal is an honest order decision: your exact HTS line, entry date, and CBP treatment decide the final bill, so confirm with official sources or a licensed customs broker before wiring a deposit.
Frequently Asked Questions
How often are the tariff rates on this site checked?
The full check runs on a regular schedule, with extra checks in the run-up to known deadline dates such as a tariff layer's scheduled expiry. The rates last verified date on the calculator only moves after a check completes.
Who checks the rates?
One person: the site owner. Monitoring tools flag what moved, but no number changes until it has been confirmed against the official text from the USITC, USTR, the Federal Register, or CBP.
What should I do if a number looks wrong or stale?
Email hello@importcostcalculator.com and it will be re-checked against the official sources. I'd rather correct a figure than have you price an order on it.
Can I use these rates for a customs filing?
No. These are planning rates for order decisions. Your final duty depends on your exact HTS classification, entry date, exclusions, and CBP treatment, so confirm with official sources or a licensed customs broker before committing money.
Planning Information Only
This page describes a verification process, not a guarantee. Tariff rules change quickly, and final duties depend on facts this site cannot know, including product classification, exclusions, origin analysis, shipment channel, and entry date. Verify current treatment with official sources or a licensed customs broker before committing money to an order.