Short answer When the country of manufacture or last substantial transformation changes, the preferential duty rate you were paying can disappear overnight. The fix is a recheck of origin data, trade agreement eligibility, and the duty rates on every affected SKU before the new stock ships, not after the first invoices arrive.
Why a supplier move is a duty event
Most duty math rests on one quiet field in your product data: country of origin. That field decides which tariff schedule applies, whether a free trade agreement reduces the rate to zero, and whether extra duties like Section 301 apply at all. When you move production from one country to another, even to a neighboring one, that field changes and the whole calculation has to be redone.
- Origin is about where the goods were made or last substantially transformed, not where the supplier's office sits. A factory move across a border changes origin; a new sales rep does not.
- Preferential rates under trade agreements vanish the moment the origin country is no longer a party to the agreement. The rate that replaces them is often the standard most-favored-nation rate, which can be several times higher.
- Extra duties are country-specific. Moving assembly out of a country subject to additional duties can cut your rate, while moving into one can add a surcharge you never modeled.
Recheck origin data first, in this order
- Confirm the new country of manufacture for each affected SKU in writing from the supplier, including where final assembly and the last substantial transformation happen.
- Check whether the product still qualifies for the same trade agreement, and whether a different agreement now applies. Qualification rules differ by product and by agreement.
- Update the origin field in your product data and ERP so the new value flows everywhere the old one did: checkout estimates, broker filings, and reporting.
- Keep the old origin records. If customs questions a shipment that straddles the changeover, you will need to show which units came from which factory.
Re-run the rate math before the first shipment
With the new origin confirmed, recalculate the duty rate per SKU per destination market. Do this at the SKU level, because a single product line can contain items with different classifications and therefore different rate changes. Then compare the new blended duty cost against your current pricing.
- Flag any SKU where the new rate pushes the unit economics negative at the current retail price. Those SKUs need a price move, a margin acceptance, or a rethink of the supplier change.
- Watch for compounding effects: a higher duty rate plus the flat per-item EU duty on low-value consignments can turn a small rate change into a large per-order change.
- Share the new numbers with whoever sets promo pricing. A promo planned on the old duty assumptions will underprice if it runs after the switch.
Tell your checkout before the first order ships
If you show delivered-duty-paid totals at checkout, the estimate layer needs the new rates before customers start ordering the new stock. Stale estimates either overcharge shoppers, which kills conversion, or undercharge them, which eats margin on every order until someone notices.
- Update the duty calculation feed or table the moment the new rates are confirmed, and test a sample checkout for the affected SKUs.
- If the changeover is gradual, make sure the checkout handles both origins during the transition. Mixed inventory is the most common source of wrong estimates.
- Log the date of the change per SKU. When the first duty invoices arrive, you will want to reconcile them against the new assumptions, not the old ones.
Questions buyers ask
Does moving assembly to a neighboring country always change the origin?
Not always. Origin depends on where the last substantial transformation happened, which is a facts-and-circumstances test, not a map distance test. Minor assembly in a new country may not change origin, while a full manufacturing move does. When in doubt, get the determination in writing and keep the analysis on file.
What if my supplier will not share origin documentation?
Push for at least a written statement of the country of manufacture per SKU. Without it, you are guessing on the most important input to your duty calculation, and customs authorities will not accept a guess. If a supplier refuses basic origin information, treat that as a commercial risk, not just a paperwork annoyance.
How often should I recheck origin on existing SKUs?
Recheck on every supplier change, every factory move, and at least once a year for your top SKUs. Suppliers quietly shift production between their own facilities more often than brands realize, and each shift is a potential origin change.