4. Duty estimates
What DutyLookout calculates
Once a product has a ten-digit code, DutyLookout builds a duty stack for it rather than showing a single percentage. A commercial entry is made up of:
| Line | What it is |
|---|---|
| Base duty | The general (MFN) rate published for that code |
| Surcharges | Programs that stack on top — Section 301 and similar — resolved by the product's country of origin |
| Merchandise Processing Fee | Ad-valorem, with the statutory minimum and maximum applied |
| Harbor Maintenance Fee | Vessel shipments only |
Rates come from the published tariff schedule, not from a model. The AI decides which code applies; every number attached to that code is looked up. A wrong figure means a wrong code, not invented arithmetic.
Because surcharges depend on origin, country of origin is the next field to fill in after a good description. Without it the base rate is still correct, but the app cannot tell you whether a Section 301 program applies. Set a fallback in Settings → Default origin country for products that do not carry their own.
Commercial vs postal
Settings → Duty estimates → Shipping mode changes the model:
- Commercial (formal entry) — the full stack above.
- Postal — some postal shipments fall under a flat simplified regime that replaces the ad-valorem stack entirely, with no MPF or HMF. DutyLookout shows the flat per-item charge instead.
Pick the one that matches how you actually ship. They produce materially different numbers.
Sample customs value
Percentages are hard to compare across products, so Settings → Sample customs value (default $100) turns rates into dollar amounts on product pages. It is a display aid for comparison — not a declared value, and changing it does not change any rate.
One thing to expect: the Merchandise Processing Fee has a statutory minimum per entry (currently $33.58), and at a $100 sample value that minimum dwarfs the duty itself. That is not an error. The fee is charged once per shipment, not per item, so it barely moves the needle on a real container and looks enormous against a single $100 unit. If you want the dollar figures to resemble your actual entries, set the sample value near a typical shipment value rather than a unit price.
What is still excluded
The estimate is a good working model of an entry. It is not a broker's quote. It does not include:
- Complete surcharge coverage. Section 301 and Section 232 cover thousands of individual tariff lines. DutyLookout does not yet carry all of them, so the absence of a surcharge line means no program in our data matched — not that none exists. The app says so on the estimate when it happens. Treat a surcharge-free estimate as a floor and check the code yourself if the origin is one you know carries a program.
- Antidumping and countervailing duties. Product- and exporter-specific, and frequently far larger than everything else combined.
- Trade-agreement preferences. USMCA and similar can reduce duty to zero if your goods qualify and you can document it. DutyLookout does not assume you qualify.
- De minimis treatment. Low-value shipments may be handled differently.
- Freight, insurance, and customs broker fees.
If a base rate reads 0%, that does not mean the shipment is duty free — it means the general rate is zero and everything above still has to be checked.
Specific and compound rates
Not every rate is a percentage. Some codes carry a specific duty — per kilogram, per litre, per dozen — or a compound of both.
Where a code carries a specific component DutyLookout flags it rather than inventing a percentage, because converting one to the other needs a unit quantity the app does not reliably have. Treat those as "go and read the line".
Using the estimates well
Good uses: comparing duty exposure across products you are considering stocking; finding a category where you have been guessing badly; a first-pass landed-cost model; spotting a rate change before it reaches an invoice.
Bad uses: a final landed-cost quote to a customer; a declared value on a customs entry; a substitute for a broker on high-value or regulated goods.
Next: Tariff alerts →