By the Zoomexpress Compliance Team — September 10, 2026 — 7 min read
Customs delays are the single greatest cause of international shipment disruptions — and the frustrating reality is that the vast majority are entirely preventable. Unlike weather events or carrier capacity issues, customs holds almost always originate in documentation errors or compliance failures that occur before the shipment even leaves its origin. Here is a breakdown of the seven most common causes and the specific steps you can take to eliminate them.
The commercial invoice is the foundation of customs clearance. A missing field — the country of origin, the Incoterm, or a vague goods description like "clothing" instead of "men's cotton woven shirts" — gives customs officials grounds to query or hold the shipment. Always describe goods by their specific commercial name, include the HS code, state the true transaction value, and ensure every field is complete before the shipment is collected.
HS codes are a globally standardised 6-digit (and country-extended) classification system used by customs to apply duty rates and enforce trade policy. Using the wrong HS code can result in incorrect duty assessment, which in turn triggers audits, reassessments, and penalties. If you regularly ship a range of products, invest in a proper tariff classification exercise conducted by a licensed customs broker.
In 2025, incorrect tariff classification was cited in 31% of all commercially-triggered customs queries in international express shipments, according to industry data.
Declaring a shipment value lower than the actual transaction value — whether to reduce duty liability, stay below de minimis thresholds, or for any other reason — is customs fraud. Most customs authorities now cross-reference declared values against market databases and flag statistical outliers automatically. Beyond the legal risk, a customs query on valuation delays every shipment in the consignment until the matter is resolved.
Goods in regulated categories — food, agriculture, cosmetics, electronics, medical devices — often require destination-country certificates or conformity declarations (CE marking, FDA registration, phytosanitary certificates, etc.). Failing to attach the required certificate means the shipment cannot be released. Research destination-country requirements for every new product type before your first shipment.
Shipping to an entity on a sanctions list — even unknowingly — will result in the shipment being frozen by customs or the carrier's own compliance systems. Run your counterparties through a recognised screening tool against OFAC, EU, UN, and UK sanctions lists before every transaction. This is not optional for any company engaged in international trade.
Lithium batteries, perfumes, aerosols, paint, cleaning products, and many other everyday items are classified as dangerous goods under IATA regulations. Sending these on passenger or cargo aircraft without proper declaration, packaging, and labelling is a serious criminal offence. Always check whether your product falls within the IATA DGR before shipping by air.
On the destination side, if the consignee lacks a required import licence, an EORI number, or fails to respond to customs' request for additional information, the shipment will sit at the port of entry accruing storage charges. Ensure your consignee is fully briefed on their import obligations — particularly for high-value or regulated goods — before the shipment departs.
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