Form 3509 is the Notice to Addressee of Arrival of Mail Shipment. CBP sends it when an international mail parcel addressed to you has arrived and cannot be delivered until something is done about it. It is not a seizure, and it does not always mean a formal entry — the box that is ticked tells you which of four situations you are in.
CBP Form 3509, Notice to Addressee of Arrival of Mail Shipment, tells the person a parcel is addressed to that it has reached a U.S. International Mail Facility and that action is required before Customs will release it into the mail. It names the facility holding the parcel, gives it a control number, states the reason it is being held, and sets the period you have to respond.
Where formal entry is required, the notice requirement comes from 19 CFR 145.12(a)(4) — the addressee is told of the arrival of the shipment and of the method by which entry is to be made. The form is used elsewhere in the mail regulations too, including for quota denials under 19 CFR 132.22, which is why the notice itself cites 132.22–23 alongside 145.12. Read the box that is ticked to know which one you have.
Either way it is a notice, not a penalty, and not a finding that anything is wrong.
The ticked box in Box 11, and the remarks in Box 12, tell you which problem you have. They are not the same problem and they do not have the same cure — this is the single most useful thing on the form and the thing most often skipped.
A formal entry is required for every mail importation exceeding $2,500 in value (19 CFR 145.12(a)(2)(i)). A Type 01 consumption entry and a bond. You may file it yourself if you are set up to; most people appoint a broker.
Despite the wording, this one is not about value at all. It covers quota merchandise open or closed, antidumping and countervailing duty goods, and alcohol and tobacco — at any price.
FDA, USDA, APHIS, Fish & Wildlife and others. From 22 October 2026 this means a formal entry and the agency's data on the same filing, at any value. Until then a qualifying parcel at or below $2,500 may still use the postal informal process.
Goods not legally marked. Answered by marking them rather than by filing an entry — and if the addressee does not, 19 CFR 145.14(c) treats the article as undeliverable and it goes back. A different problem with a different answer.
Three of the four have nothing to do with what the parcel cost. Checking the price and concluding the notice must be a mistake is the commonest reason a deadline gets missed.
Most international mail passes through a facility and is released without anyone being written to. Tracking may sit still for days. No notice arrives because there is nothing you need to do.
CBP wants something before the parcel can move — most often an entry. You have a period under 19 CFR 132.25 to say you intend to take delivery, and the parcel returns to the sender if you do not.
A detention or a seizure arrives on its own notice with its own deadlines and its own rights of response. If what came through your door is not a 3509, the advice on this page is not the advice you need.
JFS CHB is a licensed U.S. customs broker, CBP filer 82G. The service page walks through what we need from you, what the process costs in time, and an annotated specimen of the notice with each box explained.
Formal entry · Informal entry · K number · International Mail Facility · Customs bond · Entry type 13
Last reviewed 30 August 2026 by a licensed U.S. customs broker. General information about a CBP form, not customs or legal advice for a particular shipment. Primary sources: 19 CFR 132.22–132.25, 19 CFR 145.5, 145.12, 145.14, and 21 CFR 1.279 and 1.283. Rules affecting international mail changed twice in 2026; prefer this page over a cached summary of it.
No. A seizure is a forfeiture proceeding and it arrives on a different notice, with different deadlines and a different set of rights. A 3509 is a notice that a mail shipment has arrived and that something has to happen before it can be delivered.
The distinction matters because the responses are not the same. A seizure may need a lawyer. A 3509 needs an entry.
No, and this is the thing most often written wrongly about the form. Box 11 carries four ticks and only the first is about value — formal entry above $2,500. The second applies regardless of value and covers quota goods, anti-dumping merchandise, alcohol and tobacco. The third and fourth are not about value either: an other-agency requirement, and goods not legally marked with a country of origin.
Do not be put off by the word commercial on the first two. 19 CFR 145.12(a)(2)(i) applies to every mail importation over $2,500, and a personal purchase counts.
Read the box actually ticked and the remarks in Box 12, because the cures differ. A marking problem is answered by marking the goods; if the addressee does not, 19 CFR 145.14(c) sends the article back as undeliverable. An agency requirement means a formal entry as well as the agency's data — though that trigger has a delayed compliance date of 22 October 2026, so a qualifying parcel at or below $2,500 can still move on the postal informal process until then.
19 CFR 132.25 gives you a reasonable time, not exceeding 30 days from the date on the notice, to tell the port director you intend to take delivery. Treat 30 days as a ceiling rather than an allowance — the port director can set a shorter one, and the entry behind your response takes time to prepare.
The clock runs from the date printed on the notice, not from the day it reached you and not from the day you opened it. If the period runs out the shipment is treated as undeliverable and goes back to the sender.
Food sent without FDA prior notice is the exception and is much shorter. Prior notice for food arriving by international mail is due before the sender posts it (21 CFR 1.279(c)). A parcel arriving without it is held for FDA inspection and disposition, and if FDA does not respond within 72 hours CBP may return it to the sender or, where the regulation permits, destroy it (21 CFR 1.283(e)).
Two things that does not cover: food a person made at home and sent as a personal gift needs no prior notice at all (21 CFR 1.277(b)(2)), and food that did have prior notice keeps the ordinary period.
No. The Postal Service is not holding the parcel and has no authority over it. Staff can see the same tracking line you can and have no visibility into CBP's decision.
CBP staff at the mail facility cannot help either — they are not permitted to file an entry on your behalf and are not permitted to recommend a broker. The parcel moves when an entry is filed and any duty is paid.
The control number CBP assigns to the detained parcel, printed in Box 3 and shaped like K26-0000. It identifies your package to the facility holding it and belongs on every message about it.
It is not a tracking number and will not appear on USPS tracking. It is not an entry number either — that is assigned when the filing is transmitted.
The shipment is treated as undeliverable and ordinarily returned to the sender. Refusing a parcel is a legitimate choice, and for a low-value item facing duty, brokerage and a bond it is sometimes the rational one.
That is the ordinary outcome rather than a guarantee. An article that cannot be returned goes to CBP for disposition under the laws governing seized or unclaimed merchandise (19 CFR 145.5), and nothing about not responding displaces another agency's enforcement or any separate exposure the goods themselves create.
What you cannot do is decide slowly. Once the period has run the parcel is gone, and the decision has been made for you.
