Customs delays are one of the most frustrating and costly problems in international air freight. A shipment that should arrive in 24 hours can sit in a customs warehouse for days — or even weeks — due to avoidable documentation errors. Based on our experience handling thousands of shipments annually, here are the 10 most common customs mistakes and exactly how to avoid them.
Why Customs Delays Are So Costly
When a shipment is held at customs, the costs multiply quickly. Storage fees at airport cargo terminals typically start at $0.10–0.25 per kg per day. For a 500 kg shipment, that's $50–125 per day in storage alone. Add the cost of production delays, missed delivery windows, and the administrative time spent resolving the issue, and a single customs hold can easily cost thousands of dollars.
The good news is that the vast majority of customs delays are caused by preventable errors. Understanding what customs authorities look for — and ensuring your documentation is complete and accurate before the shipment departs — is the single most effective way to avoid these costly delays.
The 10 Most Common Mistakes
1. Incorrect or Missing HS Codes
The Harmonized System (HS) code is a standardized numerical classification for traded goods used by customs authorities worldwide. Using the wrong HS code — or omitting it entirely — is the single most common cause of customs delays. An incorrect HS code can result in the wrong duty rate being applied, triggering a customs examination and potentially a penalty.
Always verify HS codes using the official Turkish customs tariff database or the destination country's tariff schedule. When in doubt, consult a licensed customs broker. A 6-digit HS code is required for international trade; many countries require 8 or 10 digits for import purposes.
2. Inaccurate or Incomplete Commercial Invoice
The commercial invoice is the primary document customs authorities use to assess duties and taxes. Common errors include: missing seller/buyer details, incorrect country of origin, vague goods descriptions, missing unit prices, and incorrect currency. Every field on the commercial invoice must be accurate and consistent with the other shipping documents.
Commercial Invoice Must Include
- Full name and address of seller and buyer
- Invoice date and number
- Detailed description of goods (not just "merchandise")
- HS code for each line item
- Quantity, unit price, and total value per line item
- Currency of transaction
- Country of origin
- Incoterms (e.g., EXW, FOB, CIF)
3. Undervaluing Goods
Deliberately undervaluing goods to reduce import duties is customs fraud — and customs authorities are very good at detecting it. They use databases of typical transaction values for thousands of product categories. If your declared value is significantly below the expected range, your shipment will be flagged for examination. Always declare the true transaction value.
4. Missing or Incorrect Packing List
The packing list must accurately reflect the physical contents of each package. Discrepancies between the packing list and the actual contents — even minor ones — can trigger a full physical examination of the shipment, adding days to the clearance process. Ensure the packing list matches the commercial invoice in terms of quantities and descriptions.
5. Incorrect Country of Origin Declaration
The country of origin affects which duty rates apply and whether preferential trade agreements (such as the EU-Turkey Customs Union) can be used. Incorrectly declaring the country of origin — even unintentionally — can result in the wrong duty rate being applied and potential penalties. For goods with complex supply chains, a certificate of origin from the relevant chamber of commerce is essential.
"In our experience, over 60% of customs delays are caused by documentation errors that could have been caught with a simple pre-shipment document review. Five minutes of checking saves five days of waiting."
6. Failing to Obtain Required Permits and Licenses
Certain goods require special permits or licenses to export from Turkey or import into the destination country. These include: pharmaceuticals and medical devices, food and agricultural products, chemicals, dual-use goods, and items subject to sanctions. Attempting to ship these goods without the required documentation will result in the shipment being held — and potentially seized.
7. Incorrect Incoterms on Documents
Incoterms define the responsibilities of buyer and seller for costs, risks, and documentation. Using the wrong Incoterms on your commercial invoice can create confusion about who is responsible for customs clearance and duty payment, leading to delays while the parties sort out the issue. Ensure all parties agree on the applicable Incoterms before the shipment is booked.
8. Not Pre-Filing Customs Declarations
Many countries now require advance cargo information to be submitted electronically before the aircraft departs. The EU's ICS2 system, the US's AMS (Automated Manifest System), and similar programs in other countries require pre-arrival declarations. Failing to submit these on time can result in the shipment being held on arrival. Work with a freight forwarder who handles pre-filing as a standard part of their service.
9. Packaging That Doesn't Match the Declaration
If your shipment is declared as 10 cartons but arrives as 12 cartons, or if the gross weight on the airway bill doesn't match the actual weight, customs will flag the discrepancy. Always weigh and count your shipment carefully before preparing documents, and ensure the carrier's measurements are reflected accurately in all paperwork.
10. Using Vague Goods Descriptions
Descriptions like "spare parts," "samples," "merchandise," or "goods" are red flags for customs authorities. Every item must be described specifically enough for a customs officer to identify it and classify it correctly. Instead of "spare parts," write "stainless steel automotive exhaust manifold gaskets, 50mm diameter." The more specific, the better.
Building a Customs-Ready Shipment Process
The best way to avoid customs delays is to build a systematic pre-shipment documentation review into your logistics process. Before any shipment departs, run through a checklist:
- Verify HS codes against the official tariff schedule
- Cross-check commercial invoice, packing list, and airway bill for consistency
- Confirm all required permits and certificates are in order
- Ensure pre-filing requirements for the destination country have been met
- Verify that declared values reflect actual transaction values
- Check that goods descriptions are specific and accurate
Working with an experienced freight forwarder and licensed customs broker is the most reliable way to ensure your shipments clear customs without delays. Our team at Turkey Air Cargo includes certified customs specialists who review every shipment's documentation before it departs, catching potential issues before they become costly delays.
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