A customs bond is a financial guarantee to U.S. Customs and Border Protection that your duties, taxes, and fees will be paid — most repeat importers carry a continuous bond sized at 10% of the duties, taxes, and fees they paid in the previous 12 months (minimum $50,000), executed by a Treasury-listed surety on CBP Form 301 and filed for you by a licensed customs broker or surety agent. One-off shipments can use a single transaction bond instead, generally sized at the entered value plus all duties, taxes, and fees. The bond amount is CBP's required coverage, not the price you pay — the surety's premium is a separate, much smaller number.
If you searched "customs bond," you are probably days from a first formal entry — or you just received a letter saying your existing bond is no longer big enough. Both situations run through the same small body of rules: 19 CFR Part 113, CBP Form 301, and a short set of CBP sizing formulas.
This guide states those rules from the primary sources, then walks through the decisions that matter: which bond type to buy, how large CBP will require it to be at 2026 tariff levels, and who files it.
What a customs bond is — and what it is not
A customs bond is a three-party contract: the principal (the importer of record), the surety (an insurance company authorized by the U.S. Treasury to guarantee the principal's obligations), and CBP as beneficiary. If the importer fails to pay duties, taxes, and fees, or breaks another bond condition, CBP collects from the surety — and the surety then pursues the importer for reimbursement.
Under 19 CFR 142.4, CBP will not release merchandise on a formal entry until a single entry or continuous bond on CBP Form 301, executed by an approved corporate surety (or secured by cash), is on file. Formal entry is generally required for commercial shipments over $2,500, and CBP may require it for any merchandise where enforcement or revenue protection calls for it (19 CFR 143.22). The standard importer bond is Activity Code 1, "Basic Importation and Entry," with conditions set out in 19 CFR 113.62; other activity codes cover custodians, carriers, foreign trade zone operators, drawback, and ISF.
Two things a customs bond is not. It is not insurance for you — it protects the government's revenue, not your cargo. And the bond amount is not the bond price.
The bond amount is the coverage CBP requires the surety to guarantee — $50,000, $70,000, $200,000. The premium is the fee the surety charges you to issue that guarantee, and it is a small fraction of the amount, set by the surety's underwriting rather than by CBP. Every formula in this guide is about the amount; the premium is commercial pricing, quoted by the surety.
Single transaction vs. continuous bonds
CBP accepts two forms of the Activity Code 1 importer bond.
A single transaction bond (STB, or single entry bond) covers one entry at one port; it is what you get, shipment by shipment through the filing broker, when no continuous bond is on file.
A continuous bond covers all of the principal's entries at every U.S. port for a one-year term and renews until terminated by the principal, the surety, or CBP. It also satisfies the Importer Security Filing bond requirement of 19 CFR 149.5 on ocean shipments, so importers with more than a handful of entries a year almost always land here.
| Feature | Single transaction bond | Continuous bond |
|---|---|---|
| Coverage | One entry, one port | All entries, all U.S. ports |
| Term | The single entry, through liquidation | One year; self-renewing until terminated |
| Sizing basis | Entered value + all duties, taxes, and fees (3× value for restricted categories) | 10% of prior 12 months' duties, taxes, and fees; $50,000 minimum |
| Covers ISF (19 CFR 149.5) | No — a separate ISF bond is needed | Yes |
| Obtained | Per shipment, via the filing broker | Once, via a broker or surety agent; filed in eBond |
| Best for | One-off or test shipments | Anyone importing repeatedly or filing ISF |
How CBP sizes each bond — the exact formulas
CBP publishes its sizing rules in "A Guide for the Public: How CBP Sets Bond Amounts" (Publication 3569-0224). The two formulas that matter to importers:
Continuous bond. The minimum Activity Code 1 continuous bond amount is $50,000 or 10% of the total duties, taxes, and fees in the previous 12-month period, whichever is greater. Continuous bonds are set in increments of $10,000 up to $100,000, and in increments of $100,000 above that, rounding up. A first-time importer with no history is sized on the duties, taxes, and fees estimated for the next 12 months — never below the $50,000 floor. Informal entries and Section 321 de minimis shipments are excluded from the computation.
Single transaction bond. Generally not less than the total entered value plus all duties, taxes, and fees that apply. Two published variations: unconditionally duty-free merchandise may be bonded at 10% of entered value, while restricted merchandise must be bonded at three times its value — a multiple CBP's monetary guidelines apply to categories such as merchandise subject to certain other-agency requirements (FDA-regulated goods among them) and quota or visa merchandise.
A worked example at 2026 tariff levels
The 10% formula looks backward, which is exactly why bonds saturate faster now. Take an importer bringing in $1.8 million of goods a year. At a 4% average duty rate, that meant roughly $72,000 in annual duties, taxes, and fees — 10% is $7,200, and the $50,000 minimum bond covered it several times over.
Run the same volume through a 2026 duty stack where Section 301, Section 232, and IEEPA-based tariffs push the effective rate to 30%, and annual duties, taxes, and fees become about $540,000. Ten percent is $54,000 — past the $50,000 line — and rounding in $10,000 increments sets the required bond at $60,000. At $6 million of the same goods, the math yields $180,000, which rounds up in $100,000 increments to a $200,000 bond. Nothing changed except the tariff rate. You can run your own numbers with our customs bond calculator.
Bond insufficiency: how CBP flags it and what happens
CBP does not wait for you to notice. Under 19 CFR 113.13(c), CBP periodically reviews every bond on file for adequacy. When rising duty flow — tariff-driven or volume-driven — pushes 10% of your trailing 12 months of duties, taxes, and fees above your bond amount, CBP's Revenue Division issues a written insufficiency notice to the principal and the surety.
From the date of notification, the principal has 15 days to remedy the deficiency — for a continuous bond, CBP's guidance describes the fix as terminating the existing bond and replacing it with one in the larger required amount by the deadline in the notice. Until then, CBP may demand additional security — cash deposits or single transaction bonds — on any or all of the principal's transactions, and may require additional security immediately whenever it believes the revenue is in jeopardy.
The insufficiency letter is not a penalty — it is arithmetic — but it has a hard deadline, and a replacement bond still has to clear surety underwriting. The practical move: re-run the 10% math whenever a new tariff action touches your products, and size the replacement against the next 12 months of duty rather than the last 12. To get the exposure mapped before CBP maps it for you, a free Import Readiness Review returns duty-exposure notes per product line — the number a bond has to be sized against.
How to get a customs bond
You cannot sign a bond yourself. Under 19 CFR 113.37, a corporate surety is acceptable only if listed in Treasury Department Circular 570, the Treasury's roster of companies authorized to write federal bonds. The path in practice:
- Establish your importer record first. The bond attaches to your importer of record number, created by filing CBP Form 5106 — bond and 5106 are typically set up together during onboarding.
- Choose bond type and amount. Activity Code 1, single transaction or continuous, sized by the formulas above — for a continuous bond, against expected duties, not just historical ones.
- Buy it through a licensed customs broker or surety agent. The broker or agent obtains the bond from a Treasury-listed surety, which underwrites your account; the executed bond lives on CBP Form 301 — see our field-by-field Form 301 guide.
- The surety files it electronically. Sureties and their agents transmit single transaction and continuous bonds into ACE through CBP's eBond process (in place since January 2015), so coverage is on file before your entry is transmitted.
Greenwich Mercantile is not a surety and does not issue bonds. Bond placement is arranged and filed through licensed U.S. customs broker partners as part of importer setup, and a licensed U.S. customs broker verifies classification and entry details before anything is filed — the classification drives the duty math the bond is sized against.
What a customs bond costs
Honest answer: this page will not quote a premium, because premiums are surety pricing, not regulation. CBP fixes the amount — the formulas above. The premium depends on bond size, duty exposure, payment history, and underwriting appetite, and it moves when tariff levels move. Any dollar figure you read for "customs bond cost" is a market quote with a shelf life, not a rule.
What you can control is how the bond is bought. Ask for the amount and the premium as separate line items, ask whether procurement carries a broker handling fee — many brokers charge one, as covered in our customs broker cost guide — and ask what happens if CBP raises your required amount mid-term. Greenwich Mercantile includes bond coordination in its flat-rate customs brokerage service with no separate procurement fee; the surety's premium is the only bond cost that reaches you.
Not sure which bond your first shipment needs?
Send one commercial invoice, packing list, or product list. Greenwich runs a free Import Readiness Review and returns:
- Importer-setup gaps — IOR status, CBP Form 5106 registration, customs bond readiness, broker power of attorney
- Preliminary HTS classification with confidence levels
- Duty exposure notes — the number a bond has to be sized against
- FDA / CPSC / USDA flags per product line
- Prioritized next steps
A licensed U.S. customs broker verifies classification and entry details before anything is filed.
Frequently asked questions
How much does a customs bond cost?
The bond amount and the price you pay are two different numbers. CBP sets the bond amount — the coverage the surety guarantees — at 10% of your previous 12 months of duties, taxes, and fees for a continuous bond (minimum $50,000), or the total entered value plus all duties, taxes, and fees for a typical single transaction bond. The premium is what a surety charges to issue that coverage; it is set by the surety's underwriting, not by CBP, and scales with the bond amount. Ask for both as separate line items in any quote.
What size continuous customs bond do I need?
Take the total duties, taxes, and fees you paid to CBP in the previous 12 months and multiply by 10%. If the result is under $50,000, your bond is the $50,000 minimum. Above that, CBP sets continuous bonds in $10,000 increments up to $100,000 and $100,000 increments beyond, rounding up. A first-time importer is sized on the duties, taxes, and fees estimated for the next 12 months, with the same $50,000 floor.
Do I need a customs bond for every shipment?
You need bond coverage for every formal entry, but not a new bond each time. CBP will not release merchandise on a formal entry — generally required for commercial shipments over $2,500 — until a single transaction or continuous bond on CBP Form 301 is on file. A single transaction bond covers one entry at one port; a continuous bond covers all your entries at every U.S. port for a year and also satisfies the Importer Security Filing bond requirement on ocean shipments.
Can I file a customs bond myself?
Not on your own signature. A customs bond must be executed by a surety company listed in Treasury Department Circular 570, and bonds are transmitted into CBP's ACE system through eBond by sureties and their agents. In practice, you buy the bond through a licensed customs broker or a surety agent, who obtains it from a Treasury-listed surety and files it against your importer of record number. Greenwich Mercantile arranges bond placement through licensed U.S. customs broker partners.
What happens if CBP decides my bond is insufficient?
CBP reviews every bond on file periodically under 19 CFR 113.13(c). If it determines your bond is inadequate, CBP notifies you and your surety in writing, and you have 15 days from the date of notification to remedy the deficiency — in practice, terminating the continuous bond and replacing it with a larger one by the deadline in the notice. Until then, CBP may require additional security, such as cash deposits or single transaction bonds, on any or all of your entries.
The bottom line
A customs bond is the least negotiable document in importing: no bond, no release. The rules are mercifully short — Activity Code 1 on CBP Form 301, a continuous bond at 10% of trailing 12-month duties, taxes, and fees with a $50,000 floor, or a single transaction bond at entered value plus duties (3× for restricted goods) — and they are all published by CBP, not folklore.
The 2026 twist is that the formula's inputs have moved: tariff stacking has multiplied the duty flow the 10% formula feeds on, and CBP's periodic reviews are built to catch exactly that. Check the math before CBP does — pull your last 12 months of duties, taxes, and fees, multiply by 10%, and if the answer is anywhere near your bond amount, start the replacement conversation through a licensed customs broker or surety agent, on your timeline instead of a 15-day one.
Primary sources: CBP, "A Guide for the Public: How CBP Sets Bond Amounts," Publication 3569-0224 (February 2024); CBP Directive 3510-004, "Monetary Guidelines for Setting Bond Amounts"; 19 CFR 113.13 (amount of bond; periodic sufficiency review), 19 CFR 113.37 (Treasury Circular 570 corporate sureties), 19 CFR 142.4 (bond required for release; CBP Form 301), 19 CFR 149.5 (Importer Security Filing bond requirement); CBP Form 301, cbp.gov. Formulas and deadlines are stated as published and can change — confirm current requirements with CBP or a licensed customs broker before acting. This is operational information, not legal advice; Greenwich Mercantile is not a surety.