U.S. Customs Clearance at San Diego Port: A Complete Guide for China Importers

 

Getting through U.S. customs in 2025 and 2026 is not the same as it was three years ago. Importing from China through the Port of San Diego requires a lot of planning that many businesses are still catching up on. This is because of big changes to tariffs, the end of the de minimis exemption for Chinese goods, stricter enforcement of paperwork, and a trade environment that changes with every executive order. This tutorial tells you all you need to know, from the foundations of ports to how to keep your supply chain flowing even when policy doesn’t work with you. It covers things like tariff structures, documentation needs, duty computations, and more.

Understanding the Port of San Diego as an Entry Point

The Port of San Diego is one of California’s most important maritime gateways. It is formally run by the San Diego Unified Port District. However, it works very differently than the large container terminal complex in Los Angeles and Long Beach. The Tenth Avenue Marine Terminal in San Diego doesn’t handle a lot of containerized freight at high TEU numbers. Instead, it handles break-bulk cargo, cars, specialist commodities, and project cargo. Ten percent of all cars brought into the United States come through San Diego. The terminal also regularly handles machinery, oil and gas equipment, steel products, aviation parts, fertilizer, and seasonal agricultural imports.

This difference is important for people who buy things from China. If your goods are in normal shipping containers, you will probably come through the ports of Los Angeles or Long Beach. But if you’re importing cars, big project cargo, bulk materials, or break-bulk cargoes, San Diego can be a faster and occasionally less crowded option. The U.S. has control over the port. The San Diego Field Office of Customs and Border Protection (CBP) is in charge of the busy land border crossings at San Ysidro and Otay Mesa.

The Port of San Diego handled 1.5 million metric tons of cargo during January to August 2025. This was a 1% increase from the same time the year before. Compared to bigger West Coast ports, the port has stayed very stable. This is partially because, as the port’s maritime director said, its lines of business aren’t as closely related to goods from China as the ports of Los Angeles and Long Beach.

The 2025–2026 Tariff Landscape: What China Importers Must Know

If there is one thing that has changed the relationship between China and the US, The tariff environment has made it harder to import things in recent years. The existing system is complicated, changes quickly, and can have big financial effects if you don’t understand it. Anyone who wants to sell goods in the U.S. through San Diego or any other port needs to know how this system works before they send out their first shipment from China.

As of April 2, 2025, the “Liberation Day” program put a 10% baseline tax on imports from all countries. Higher rates were put on countries with big trade deficits. For China, things got a lot more complicated in 2025. Tariff rates went up a lot before a temporary truce was reached. The U.S.-China tariff truce that went into effect set the maximum U.S. levies on Chinese goods at 30% until November 2025. However, important tariff acts were still being challenged in court.

Importers have to deal with Section 301 duties on top of the regular tariffs. These duties have been in effect since the first trade war. These extra Section 301 charges, which vary from 7.5% to 25%, are applied on a lot of commodities that come from China. They were put in place because of trade practices that were seen as unfair and affected a wide range of goods. When you add up the usual MFN taxes, Section 301 tariffs, and any anti-dumping or countervailing duties that apply, your effective duty rate on a product from China might be more than 30%.

The de minimis exception for goods from China will no longer be in place in 2025, which is another important development. Starting in 2025, shipments from China or Hong Kong will no longer be able to use the de minimis exemption for items worth less than $800. Starting on August 29, 2025, importers will have to follow formal entry procedures and pay tariffs on shipments that used to be free under the $800 level. This has had a big effect on cross-border e-commerce sellers who used to depend on little parcels coming in duty-free.

Required Documentation for U.S. Customs Clearance

In the United States, getting through customs is mostly about filling out paperwork. Every commercial cargo must have a comprehensive and precise paper trail, and in 2025, the agency stepped up its enforcement, especially for commodities that come from China. Invoices, packing lists, bills of lading, and purchase orders must all convey the same story. This is very important. Words like “parts” or “samples” that aren’t clear are red flags that lead to inspections.

The commercial invoice, packing list, bill of lading (or airway bill for air freight), and CBP Form 7501 Entry Summary are the most important documents for any commercial import. You will also need to complete an Importer Security Filing (ISF 10+2) for ocean shipments coming from China. You have to file your ISF at least 24 hours before the ship leaves China to avoid fines of up to $5,000 for each infringement. Many first-time importers miss this important deadline: the paperwork must happen before departure, not before arrival.

There is also a somewhat new requirement that applies just to Chinese goods that is worth noting. Starting on March 18, 2024, all shipments of goods made in China must include the factory’s ZIP code. This is a rule from CBP that stops goods made in the Xinjiang region from coming into the U.S. The Uyghur Forced Labor Prevention Act (UFLPA) says that commodities from Xinjiang are created with forced labor unless proven otherwise. This requirement is closely related to that law. You have to follow these rules, and if you don’t, your cargo could be stuck for weeks until you find out where the plant is.

The Customs Bond Requirement

A customs bond is a financial promise that the importer will follow all rules and pay all taxes, tariffs, and fees. It is required for commercial imports worth more than $2,500 or that are subject to federal rules. Most companies that regularly import goods into the U.S. need this. There are two kinds: a single-entry bond, which only covers one shipment, and a continuous bond, which covers all shipments over a 12-month period. The continuous bond is nearly always the better alternative for businesses who import goods more than once a year because it saves money and makes things run more smoothly.

The Customs Clearance Process: Step by Step

Importers may plan ahead, avoid the last-minute rushing that causes cargo delays and demurrage fines, and know what to expect when they travel through U.S. customs clearance. There are three steps in the process: before arrival, arrival, and after admittance.

Compliance before arrival starts as soon as your goods leave the factory in China. At this point, the freight forwarder should be using the Automated Commercial Environment (ACE) technology to help with the ISF filing. All business paperwork must be finished well before the ship leaves. An incomplete commercial invoice or a packing list that doesn’t match the bill of lading are two of the most typical reasons why shipments are flagged for extra inspection when they arrive.

When the ship gets to port and the entry is lodged, CBP gives the consignment a processing channel. Most entries get an immediate “line release” or automated release through the ACE system, and they don’t have to be checked in person. A smaller number of them are given a “CF28 request” to review documents, and an even smaller number are physically examined, which can range from a short tailgate inspection to a full devanning of the container. In 2025, physical inspections are increasingly regular, and if the paperwork isn’t thorough and consistent, cargo can be delayed for a week or more.

When CBP gives the go-ahead, the importer has to pay all the tariffs and fees that apply. Liquidation, which is CBP’s final decision on how much duty is owed, usually happens within a year of entry. For up to five years following a shipment, CBP can ask for proof of the shipment. This is why it’s important to keep good records. You should keep all customs-related paperwork for at least five years.

Partner Government Agency (PGA) Requirements

The role of Partner Government Agencies (PGAs) is one of the most complicated things that first-time importers to China don’t realize. CBP doesn’t work alone; it enforces the entry regulations of many federal agencies. A shipment can pass CBP’s own examination but still be halted by a PGA hold.

The FDA, CPSC, EPA, USDA, and FCC are all PGAs that CBP enforces rules for. A PGA can still halt a cargo even if it has already cleared Customs. Importers should figure out what they need early on in the sourcing process and get pre-clearances whenever they can. The FDA needs to register foreign food facilities that make food items. Electronics must pass FCC certification tests. The CPSC has rules for testing and certifying toys and other products for kids. The USDA inspects agricultural products and often requires phytosanitary certificates.

Before you make a final decision about where to get your goods, the best thing to do is to look into what the PGA needs. It’s expensive and stressful to find out that your product needs an FDA pre-market notification after it has already shipped from China. When you’re looking at suppliers, not when your container is at the terminal, is the best moment to figure out what you need.

HTS Classification and Duty Calculation

The Harmonized Tariff Schedule (HTS) is what the U.S. uses to figure out how much customs duty to charge. Every product that comes into the United States gets a 10-digit HTS code. This number tells you what the duty rate is, if there are any unique tariff treatments, and if there are any extra duties like Section 301 or anti-dumping. One of the most expensive mistakes an importer can make is getting the HTS code wrong.

One of the quickest ways to get the attention of CBP is to misclassify items. Importers have had to pay 15% of the value of their shipment because their HTS code was wrong by just one digit. In addition to the fine, misclassifying can lead to a formal audit, hold up future shipments, and leave a compliance history that CBP will remember. Not merely trust the supplier’s suggested classification, which may be based on Chinese export codes instead of the U.S. import schedule. Every importer should check their HTS codes with a registered customs broker.

To get a better idea of how duties add up, look at this example computation for a common consumer electronics item from China. The base MFN rate may be 0%, but Section 301 duties could add 25%, and the Liberation Day baseline could add another 10%, making the effective rate 35% of the declared customs value. That means $35,000 in tariffs before any state taxes or port fees on a shipment worth $100,000. At these prices, a 10% undervaluation on the business invoice that used to save a few thousand dollars is now a far more appealing and well watched activity.

Common Mistakes China Importers Make at U.S. Customs

Even experienced importers make mistakes when it comes to customs clearance, and these mistakes are more costly than ever in today’s strict enforcement climate. There are a few common problems that cause delays, fines, or cargo holds.

The most common compliance issue is still filing an ISF late or not at all. The 24-hour pre-departure requirement seems simple, but in reality, it means that your freight forwarder needs to have all the correct shipper information, HTS codes, and cargo details before the ship leaves, not when it gets to the U.S. port. If any of those data elements are missing, the ISF files are incomplete. Importers who handle many shipments a month can easily rack up $5,000 in CBP fines for each infringement.

Another ongoing issue is undervaluing commodities, especially since duty rates will be higher in 2025. The commercial invoice must show the real value of the transaction, which is the price that was paid or will be paid for the items. CBP pays close attention to things like transfer pricing agreements, transactions between connected parties, and invoices that simply show the cost of making something instead of the entire purchase price. The agency maintains statistical criteria for most types of products. If an invoice comes in far lower than those benchmarks, it is automatically reviewed.

Not knowing what the PGA criteria are before bringing in a product for the first time is another common mistake. A lot of importers find out that their product needs to be registered with the FDA, tested by the CPSC, or certified by the FCC only after their shipment has already been held at port. If you include a PGA compliance checklist in your product sourcing process before you make the purchase, you won’t have any of these problems at all.

Finally, bad record-keeping is a problem that is only obvious during a CBP audit. It is best to keep any customs-related documents for at least five years, since CBP can ask for it years after a shipment. This includes not just the import documentation but also supplier contracts, quality certifications, certificates of origin, and any letters or emails about the items’ production and value.

Strategies for Navigating Tariff Uncertainty in 2025–2026

It’s really hard for China importers to plan around the tariffs that will be in place in 2025 and 2026. Policies have changed many times in a single quarter, and the legality of some tariff moves is still being decided in court. That being said, experienced importers and logistics companies like Topway Shipping have come up with ways to limit their risk and keep their supply chains running smoothly.

One legitimate method that you should talk about with your customs broker is first-sale valuation. Using this method, the customs value is based on the amount paid for the first sale in the export supply chain that wasn’t between the manufacturer and the middleman. This is usually the case. If there are many layers in a supply chain, this can make the dutiable value much lower. The technique needs to be documented and planned ahead of time, but it follows all CBP laws when set up correctly.

Duty drawback is another useful tool for importers who make things in the U.S. or send them back out. If you bring parts from China into the U.S., put them together, and then send the finished product back to China, you could be able to get back up to 99% of the duties you paid on the parts. The application is hard to manage, but it’s worth the money for organizations who do a lot of re-exporting.

The most talked-about supply chain response to China’s tariffs has been to diversify the country of origin. The Port of Los Angeles has seen its share of imports from China drop from about 60% to 40%. This is because suppliers from Southeast Asia, such as Vietnam, Malaysia, Cambodia, Indonesia, and the Philippines, have gained ground. But for many types of products, China’s manufacturing ecosystem, infrastructure, and production capacity are still hard to copy in other places, and tariffs alone haven’t changed where companies get their specialized or complicated items.

Lastly, high-volume importers should look at getting C-TPAT (Customs-Trade Partnership Against Terrorism) certification. Being a member of C-TPAT can mean fewer cargo inspections, faster clearing times, and a lower risk profile with CBP. Getting the certification demands a real commitment to supply-chain security standards, but the operational benefits grow over time as you create a trusted importer profile with CBP.

Working with a Customs Broker vs. a Full-Service Freight Forwarder

One of the most useful choices an importer from China has to make is whether to hire a licensed customs broker on their own or a full-service freight forwarder who can handle both the logistics and the customs clearance. There is no one ideal answer for everyone. The optimal option for you will depend on how many shipments you have, how complicated the products are, and how much direct control you desire over each step of the import process.

The main job of a licensed customs broker is to make sure that all rules are followed. They sort your items, file entry papers, talk to CBP for you, and make sure that all the right duties are paid and calculated. A standalone broker arrangement works well for importers who know what products they want to buy and have good ties with their carriers. You choose the carrier and handle the logistics on your own, while the broker focuses on what they do best: compliance.

Topway Shipping is a full-service freight forwarder that offers an all-in-one solution. They handle everything from booking ocean freight to consolidating cargo in China to filling ISF forms to coordinating customs clearance to storing goods to delivering them to their final destination. This integrated strategy gives increasing importers and cross-border e-commerce enterprises a lot of operational benefits. When something goes wrong in international logistics, which will happen, there is only one point of accountability, one set of monitoring data, and one relationship to manage.

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