What changes when one cost assumption fails?

A landed-cost figure is a conclusion, not a fact. It is built from prices someone supplied, estimates someone made and amounts calculated from both. Two totals for the same shipment can differ by five figures and still both be arithmetically correct. The useful question is which assumption moved, and what evidence would settle it.

1. Put the same shipment in both columns

The worked example on this site uses one hypothetical shipment: 120 cast-steel gate valves, USD 186,000 FOB Busan, proposed for an exclusive distributor in Surabaya. Nothing about the goods, the quantity or the route changes between the two scenarios. One assumption does: whether the certificate of origin is accepted for the preferential-duty scenario.

Hypothetical 120-valve shipment. Illustrative economics, not a quote, and not a prediction of either certificate outcome.

Both totals answer the same narrow question: how much cash this shipment requires under this scenario. The second column is not a worse product or a worse distributor. It is the same shipment with a different assumption, and the difference is the price of that assumption inside this model.

2. Separate supplied prices from estimates and derived amounts

Before comparing totals, label each line: supplied, estimated or derived. A supplied line has a document behind it, such as the invoice value. An estimated line rests on a stated basis, such as freight at a quoted rate. A derived line is calculated from the other two, such as duty and related tax amounts. A total that mixes the three without labels hides which part is actually known.

In this hypothetical example, the goods value is an assumption held identical in both columns, not a verified supplier invoice. What changes is the treatment that follows from the certificate outcome, and every line that depends on it. That is why the label matters more than the headline: a supplied number keeps its value in both scenarios, while a derived number moves with the assumption.

3. Change one assumption at a time

Change one assumption, hold everything else, and note which lines move. If two things change at once, the difference cannot be attributed. Here the single change is the certificate outcome, and the total cash outlay moves from USD 231,470 to USD 242,891. The difference is USD 11,421.

That figure is a scenario delta. It is not money saved, money lost or a forecast of what a shipment will cost. It is the price of one assumption inside this model, and it exists only while every other line is held still.

4. Inspect the dependent lines

When the certificate treatment changes, duty and related tax amounts change with it, and anything calculated from them follows. Compare the columns line by line rather than arguing about the headline. A dependent line that moved without explanation is a gap in the model, not a rounding difference.

This is also where assumptions get tested. If the certificate is rejected, which lines become uncertain? If it is accepted, which costs are still provisional? The answer belongs beside the number, not in a footnote that nobody reads before signing.

5. Cash outlay is not final economic cost

Total cash outlay is the cash required for the shipment, including the goods, freight and estimated import charges. It is not just cash paid at the border. Final economic cost is a different question, because some of that cash may be recoverable later depending on the importer's own tax position. This example does not model that question, and this guide does not tell you that any tax is or is not recoverable. Treat the total as a cash requirement, not as the final cost of the goods.

Before you rely on either number

Write down the assumptions, then the evidence that would confirm or remove each one. Ask for the document, the date it was read and the person who can confirm it. A number without that record is a negotiating position, not a cost model.

What to do next

Start with the existing worked example for the dated rule lines and the full cost comparison, then list the assumptions your own shipment depends on. If a mandatory requirement behind one of those assumptions remains unresolved, hold the commitment that depends on it until it is resolved.