When Customs Stalls, Your Goods and Cash Freeze in Place
The Complete Guide to China Import Customs Clearance — From Declaration to Duties, Inspection, and Release

Hello, this is GreenFrog Seoul.

"Customs sent a message saying there's a problem with our paperwork — but I can't figure out what they mean."
"Can I declare a lower invoice value to save on duties?"
"This is my first import — can I file the declaration myself, or do I need a customs broker?"

Moving goods from China to Korea looks simple on paper: the factory ships, a vessel carries it, you pick it up at Busan or Incheon port. But from the moment goods arrive in port, a sequence of steps — import declaration, review, inspection, tax payment, and release — has to run cleanly in order. One stuck step and your goods sit in a bonded warehouse, racking up storage fees, while your delivery schedule slips.

Customs clearance is not just "pay your taxes and you're done." Document accuracy, correct HS classification, completed import requirements, and timely payment all have to line up before goods come out. GreenFrog Seoul breaks down the entire clearance flow — and the spots where it most often breaks down — in a single page.

This guide covers: the seven-step clearance flow, a required-document checklist, how duties and VAT are calculated, the types of customs inspection and how to respond, what qualifies as quarantine cargo, how to work with a customs broker, and the most common mistakes first-time importers make.

1. The Seven-Step Clearance Flow

2. Required Documents Checklist

Core Documents (Every Shipment)

Conditional Documents (By Product/Situation)

3. Duty and VAT Calculation

Dutiable Value (CIF Basis)

Korea calculates the dutiable value on a CIF (Cost + Insurance + Freight) basis — the FOB price plus ocean freight and insurance from China to Korea.

Customs Duty

Duty = Dutiable Value × Duty Rate
Duty rates range from 0% to 16% depending on the HS code. Check the exact rate for your product on Korea's Customs Law Information Portal (customs.go.kr) before sourcing. The Korea-China FTA can reduce duty to 0% on many items, but you need a valid certificate of origin.

Import VAT

VAT = (Dutiable Value + Duty) × 10%
Import VAT is levied on the duty-inclusive value. If you're a registered business, you can claim it back as input tax credit — but you still need the cash on hand at payment time.

Example Calculation

4. Types of Customs Inspection and How to Respond

Practical Tips to Lower Inspection Probability

• Item description, quantity, and weight must match exactly across invoice, packing list, and B/L
• First-time shipments and new product lines face higher inspection rates — as your track record builds, document-only clearance becomes more common
• If the HS code falls in a high-inspection category (dangerous goods, food, children's products), pre-attach the relevant import requirement documents

5. Quarantine — Which Products Get Held

6. Working With a Customs Broker

Importers can legally self-declare, but for complex products or first-time shipments, a licensed customs broker is far faster. Brokers handle declaration filing, HS code confirmation, import requirement checks, and customs response — all in one.

How to Choose a Broker

• Category experience: Food, electronics, chemicals — import requirements differ by product type. A broker who regularly handles your category knows the pitfalls
• Port proximity: Busan port → Busan broker; Incheon → Incheon area. Proximity matters when responding to physical inspections
• Fee range: KRW 50,000–150,000 per shipment is typical. If the price is unusually low, check exactly what's included

7. Common Mistakes — What We've Seen in Practice

① Copying the Chinese HS Code Directly

Taking the supplier's 6-digit Chinese HS code and using it for the Korean declaration. The first 6 digits are internationally consistent, but Korea's final 4 digits (HSK) differ — and those 4 digits determine the duty rate and import requirements. Always confirm the full 10-digit code against the Korean tariff schedule.

② Incomplete Import Requirements

Finding out that KC certification, radio certification, or MFDS registration is required only after the goods land. The declaration stalls, storage fees pile up, and completing the requirements can take weeks or months. The check happens before you source, not after.

③ Missing the Certificate of Origin

To apply Korea-China FTA preferential rates, you need a C/O. Requesting it after shipment is often too late. Ask the supplier at the order stage.

④ Mismatched Documents

Invoice quantities that differ from the packing list, or product descriptions that don't match the B/L. Customs will request corrections, adding days to clearance. Always cross-check all three documents before the shipment leaves China.

⑤ Not Having Cash Ready for Taxes

The tax notice arrives almost simultaneously with declaration acceptance. Filing without the funds ready means late-payment surcharges. Calculate the expected duty and VAT at the sourcing stage and reserve the cash.

Closing — Customs Clearance Is a Sourcing Decision, Not a Port Decision

Most clearance problems originate at the sourcing stage, not the port. The "we'll figure it out when it arrives" approach almost guarantees storage fees and delayed deliveries.

To sum up: confirm the 10-digit HS code and import requirements before placing the order; request the certificate of origin before loading; cross-check invoice, packing list, and B/L for consistency; include duty and VAT in your landed cost calculation from day one; send documents to your broker the moment loading is complete; and for quarantine-subject goods, complete all agency procedures before the shipment departs. GreenFrog Seoul works alongside Korean importers through every step — from pre-order requirement checks and document preparation to broker coordination and end-to-end clearance support. First shipment or hundredth, reach out anytime you hit a wall.