Most holds are about documents, and they clear fast
The most common hold in parcel traffic is the boring one: something in the paperwork doesn't line up. The commercial invoice says 400 units, the packing list says 390. The freight bill and the entry don't match. The ISF — the 10+2 filing that has to reach CBP before the vessel departs — was submitted a day late. Customs isn't accusing anyone of anything; it simply can't complete the picture, so it holds the goods until the picture is complete. These holds are the easiest to clear and the most common, which is why the first question to ask when anything gets held is never "what did I do wrong" but "which document is missing." The US import customs guide lists what a clean entry should carry, and the answer is usually in there.
The undervalued invoice: the pattern that gets everyone examined
The second cause deserves its own paragraph because it is the one that turns routine holds into expensive ones. A commercial invoice declaring $5 for a product that sells for $40 is the single most inspected pattern in international parcel traffic. CBP keeps a database of typical declared values for the same goods from the same regions, and a number that doesn't fit the pattern triggers an exam — not because any official saw your shipment, but because the number itself is a statistical outlier. Most of these cases end the same way: the value gets corrected, the duty difference gets billed, and the damage is the delay, not the outcome. The version that does not end well is the one where the importer, at this point, asks the supplier to "issue a new invoice with a better number." A corrected document that makes the goods appear to be something they are not is no longer a paperwork issue; it is a fraud issue, and it converts a fixable hold into a penalty. If you want to see what an honest value looks like when it flows through a price, the DDP pricing calculator runs the numbers both ways.
When the hold is about the goods themselves
The deeper holds start with classification and origin. A 10-digit HTS code that doesn't match what's in the box — filed wrong, or filed by the supplier under their export logic rather than the destination's import rules — is the classic trigger, and the HS code guide exists precisely because that step is where most mistakes live. Origin is the harder version of the same problem: a country-of-origin claim that doesn't match the manufacturing evidence, or a shipment pattern that looks like goods routed through a third country to dodge Section 301, produces the holds that ask for production records, not a corrected invoice. And the fastest-growing corner of this bucket is the UFLPA, where goods assembled anywhere from Xinjiang-origin inputs are held on forced-labor grounds — the hold isn't about the country on the label, it's about the supply chain behind it, and clearing it means documenting the chain, not relabeling the box.
Then there are the holds that have nothing to do with the tariff schedule at all. In the US, CBP detains goods at the border for other agencies: FDA for food, cosmetics and medical devices, CPSC for consumer products, FCC for anything that emits radio signals, USDA for plants and animal products, EPA for chemicals. A seller of LED grow lights we know had a shipment held for weeks before anyone realized the question wasn't from CBP at all — it was an FCC authorization the product never had, and no amount of customs paperwork would have answered it. The tracking status says customs, but the agency asking the question has its own rulebook, and sending them the right document is the entire game: an FCC grant, a CPSC test certificate, an FDA registration. Knowing which agency is asking changes what you send.
What happens inside the 30-day window
Detention in the US follows a recognizable sequence. CBP issues a notice — for trade-remedy and enforcement holds, typically a CF-28 request for information; for agency referrals, the referring agency's own notice — and the importer of record, you, not the forwarder, has a defined window to respond: usually 30 days, with one extension available if you ask before the deadline. The response is a documentation package: the corrected invoice, the classification reasoning, the origin evidence, whatever the specific question asks for. From there one of three outcomes: release; release with a reclassification and a duty adjustment; or referral to formal penalty and possible seizure proceedings.
Two realities decide how it plays out. First, the burden of proof is on the importer. Customs does not have to prove the entry is wrong; you have to prove it is right, and the quality of your records decides the outcome. This is the same five-year record rule the importer of record guide describes, and it is exactly when those records earn their keep. Second, time is the real cost. A routine documentation hold costs a few days; a UFLPA or AD/CVD hold can run months, with storage and demurrage accruing the whole time. For a seasonal product, a two-month hold is not a delay, it is a lost season — and the decision to abandon the goods rather than pay the storage is a real decision some importers end up making.
What to do when it's your tracking number
Start by reading the notice and answering the question it actually asks — half the delay in holds comes from importers responding to the wrong question, sending a packing list to an agency that wanted a test certificate. Route everything through your broker, who filed the entry and knows what the specific port expects. Assemble the full package in one pass rather than drip-feeding documents, because every round-trip costs days. And if the hold is from a second agency, confirm which one and send them exactly what their rulebook wants.
The don'ts are shorter and matter more. Don't have the supplier "fix" the invoice to make the numbers look better — that's the fraud line described above. Don't push the courier to "release it anyway"; couriers do not override customs. Don't assume a hold means seizure, but equally don't assume every hold is routine — if the notice references UFLPA, AD/CVD, or IP rights, treat it as serious and get professional help early, because those are the holds where the response window and the penalty scale are both unforgiving. And don't let the goods sit while you deliberate; storage charges accrue from day one.
How to avoid the hold in the first place
Every cause above is preventable, and the prevention is the same short list every time: declare the real value, file the correct 10-digit HTS code with the reasoning on file, keep origin documentation that matches the claim, and check before shipping whether your product falls under an agency's jurisdiction — FDA and CPSC rules are knowable in advance, and not knowing them is not a defense. Sellers who run that list once per SKU, before the first order, rarely see their tracking stuck at "held in customs." Sellers who skip it learn the list the expensive way, which is to say: on the phone with a broker, watching demurrage accrue on a container they can't touch.
Frequently Asked Questions
How long can customs hold a package?
Routine documentation holds typically clear in a few days to two weeks. Agency referrals (FDA, CPSC) and enforcement holds (UFLPA, AD/CVD, IP) can run weeks to months. There is no fixed statutory limit on most holds — the clock is on the importer to respond, and storage charges accrue the entire time.
Is a customs hold the same as a seizure?
No. Detention is a review hold and most end in release, possibly with a corrected duty bill. Seizure is a formal forfeiture action that follows a confirmed violation, and it comes with its own legal process. A tracking status of "held" is detention; you will know if it escalates.
Who is responsible for responding to a hold?
The importer of record. Your broker files and manages the response, but the obligation — and the records behind it — belongs to you. The importer of record guide explains why the name on the entry is the name on the hook.
Can I get my package back if it's been seized?
Sometimes. Seizure begins a process with specific deadlines — petition for relief, and in some cases judicial review — and outcomes range from release to forfeiture. The window is short and the procedure is formal; if you receive a seizure notice, this is the moment to engage a customs attorney, not a forum post.