Components from three countries, assembly in a fourth: split shipments break simple landed cost models. How to allocate freight and duty across origins correctly.
Most landed cost models assume one origin, one shipment, one clean allocation. Reality is messier: components from Vietnam, packaging from China, and final assembly in Mexico, all converging on your US warehouse. Each leg has its own freight cost, its own duty rate, and its own timing. A model that averages these into a single per-unit cost is not simplifying; it is guessing.
Split shipments break the two assumptions simple models rely on. First, that freight can be allocated evenly. It cannot, because a forty-foot container of dense components and a half-empty container of bulky packaging have wildly different cost-per-unit profiles. Second, that duty is a single rate. It is not, because each origin country's goods carry their own classification and rate, and the assembly country's transformation may or may not change the origin determination.
Start by costing each leg independently. Ocean or air freight from each origin to the consolidation or assembly point is its own line item, allocated to the units on that leg by the driver's choice: weight, volume, or value, whichever best reflects how the freight is actually priced. Dense, heavy components should carry freight by weight. Bulky, light packaging should carry it by volume. Using one driver for everything is where the distortion creeps in.
Do not forget the hidden legs. Inland freight from the factory to the port of origin, port handling at each transfer, and the final inland leg to your warehouse all belong in the model. Brands routinely undercount landed cost by 5 to 10 percent by modeling only the ocean freight and the duty. The unglamorous middle miles are real money.
Duty must be calculated per origin, per SKU, before any assembly transformation. Each component's value, classification, and origin determine its duty at the time it crosses the border where duty is assessed. If assembly in a third country is substantial enough to confer new origin, the finished good may be dutiable as a product of the assembly country instead, which can help or hurt depending on the rates.
This is where documentation discipline pays for itself. You need the value breakdown by component, the origin of each, and the assembly records showing what transformation occurred where. Without that paper trail, you cannot defend the duty calculation on audit, and you cannot optimize it either. Many brands discover, once they model properly, that shifting one component's origin changes the total duty more than renegotiating freight rates.
Structure the model as legs and allocations, not as a single spreadsheet cell. Each origin-to-destination leg gets its own cost lines; each allocation rule is explicit and documented. When a freight rate changes or a supplier moves, you update one leg, not the whole model. This modularity is what separates a model that survives contact with reality from one that is rebuilt every quarter.
Reconcile against actuals monthly. Compare the modeled landed cost per SKU against the real invoiced costs, and investigate variances above a threshold. The reconciliation is where the model earns its keep: it surfaces the supplier whose invoices drift, the lane whose rates crept up, and the allocation rule that stopped matching reality. A landed cost model is not a document; it is a process.
Because freight and duty do not split evenly. A container of dense components and a half-empty container of bulky packaging have very different cost-per-unit profiles, and each origin's goods carry their own duty rate. Averaging flattens these differences and misstates the true cost of every SKU, which corrupts pricing and margin decisions.
Match the driver to how the freight is actually priced. Use weight for dense, heavy goods and volume for bulky, light goods. Value-based allocation works for insurance and some handling charges. The key is choosing deliberately per leg rather than defaulting to one method everywhere, and documenting the choice.
Each component's duty is assessed on its own value, classification, and origin at the relevant border crossing. If assembly in a third country is substantial enough to confer new origin, the finished good may be dutiable as a product of the assembly country. You need the value breakdown by component and origin to calculate and defend this.
Monthly, against actual invoiced costs per SKU. Investigate variances above your threshold: they reveal drifting supplier invoices, creeping lane rates, or allocation rules that no longer match reality. The reconciliation loop is what keeps the model accurate; without it, even a well-built model decays within a couple of quarters.