Cross-Border Trade & Import Calculators

An HS code (Harmonized System code, sometimes called an HS tariff code or commodity code) is a standardised numerical classification assigned to every internationally traded product. The system is maintained by the World Customs Organization and used by more than 200 countries and territories. The first six digits are universal — any importing country will recognise the same six-digit heading for the same product type. Importing countries then add further digits to create their national tariff classifications (8 digits in most countries; 10 in the US and UK).

The HS code for a product determines its applicable duty rate, any quota restrictions, any anti-dumping or countervailing duties, and whether specific licences or permits are required to import it. Getting the HS code right is therefore the starting point for any import cost estimate.

Example: Chapter 90 covers optical, photographic, and medical instruments. Heading 9405 covers lamps and lighting fittings. Subheading 9405.10 covers chandeliers and other ceiling or wall light fittings. A buyer importing LED ceiling lights from China to the UK would use HS subheading 9405.10, which currently attracts a 3.7% import duty rate in the UK Global Tariff. The same product from a country with a UK FTA may attract a 0% preferential rate — but only if a valid proof of origin is provided.

HS codes must be declared on the import entry. Mis-declaration — even accidental — can result in under- or over-payment of duty, penalty assessments, and delayed clearance. Always confirm the correct HS code with a licensed customs broker before an import declaration is made.

Import duty (also called customs duty or tariff) is a tax levied by the importing country's customs authority on goods crossing the border. Most import duties are ad valorem — calculated as a percentage of the customs value of the shipment. The customs value is not necessarily the invoice price: most countries (UK, EU, Australia, Singapore, UAE) calculate duty on a CIF basis — the cost of the goods plus international freight plus insurance. The United States calculates duty on a FOB basis — the invoice price at the port of export, excluding international freight and insurance.

The duty rate that applies depends on three factors: (1) the product's HS code, (2) the country of origin of the goods, and (3) whether any free trade agreement applies between the exporting and importing countries. The default rate — called the Most Favoured Nation (MFN) rate — applies where no FTA is in place. Preferential rates under FTAs can significantly reduce or eliminate duty, but require a valid certificate of origin or other proof of preferential origin.

Import duty formula (ad valorem):

Worked example: A UK importer brings in 500 LED ceiling lights from China. Invoice value: £9,000. Sea freight: £480. Marine insurance: £28. CIF customs value: £9,508. UK duty rate (HS 9405.10): 3.7%. Import duty: £9,508 × 3.7% = £352. If the importer is VAT-registered, the 20% import VAT (£1,972) is reclaimable and is not a real cost — it is a temporary cash flow item. Total non-reclaimable landed additions: £352 duty + £120 broker fee = £472 on top of the £9,508 CIF cost.

Anti-dumping duties and countervailing duties are additional tariffs that can apply on specific products from specific origins — most commonly on Chinese-origin goods in the UK and EU. These can be substantially higher than the standard MFN rate and must be checked separately. They are not reflected in standard duty rate databases.

Landed cost is the total cost of a product by the time it arrives at your warehouse or fulfilment centre. It includes every cost incurred between the supplier's factory and your stock location. Using the ex-works or FOB price as the cost base for margin calculations is one of the most common — and most expensive — errors in import buying.

Landed cost components:

Worked example: 500 units imported at £14 ex-factory. Sea freight £850, marine insurance £24, import duty £394 (5%), broker fee £120, port handling £180. Total landed cost: £8,568. Landed cost per unit: £17.14 — 22% higher than the factory price. A business that sets its retail price based on the £14 factory price is understating its cost by 22%.

Landed cost is also the input for gross margin on imported goods. Margin is always calculated on the net selling price minus the fully-landed cost — not the factory price. If freight rates change significantly (as they did between 2021 and 2024), landed cost models must be updated to reflect the current freight rate, not the rate at the time the product was first priced.

Cross-border seller margin is the gross margin a business achieves on imported goods, calculated using fully-landed cost rather than purchase price. It is the correct measure of import profitability and is directly affected by changes in freight rates, duty rates, exchange rates, and customs value bases.

Formula:

A common mistake is to use the invoice price as "cost" when calculating margin. If a product costs £14 ex-factory but has a landed cost of £17.14 per unit, and the selling price is £32, the margin calculation differs substantially:

The 9.9 percentage point margin difference represents real money — in a business turning over £500,000 in imported goods revenue, it equals approximately £49,500 in misattributed profit. Decisions made on the wrong cost base — product mix, pricing, promotional discounts — can all result in actual losses that the P&L does not explain until a proper landed cost audit is done.

For businesses selling into DDP markets (where the seller pays duty on behalf of the end customer — common in B2C cross-border e-commerce), the duty and import VAT are also a cost to the seller and must be included in the price charged to the consumer.