Customs Bond Types: Continuous, Single Transaction, and ISF Bonds

Key Points

• CBP requires a customs bond on every formal entry; the bond is a legal contract among the importer, a Treasury-approved surety, and CBP that guarantees payment of duties, taxes, and fees.
• A continuous bond stays in force until terminated, covers all entries and ISF filings, and carries a minimum amount of $50,000, generally set at 10 percent of the duties, taxes, and fees paid in the prior twelve months.
• A single transaction bond covers exactly one entry; the bond amount is tied to the entered value plus estimated duties, taxes, and fees, and is set higher when the merchandise is subject to other agency requirements or quota.
• A separate ISF single transaction bond is available for importers who need to file an Importer Security Filing without an active continuous bond on file.
• If CBP determines that a bond is no longer sufficient, it issues a bond insufficiency notice; the importer must increase the bond or new entries will be held.

On this page

1. What a customs bond is and why CBP requires one
2. Continuous bonds: how they work, coverage, and amount
3. Single transaction bonds: when to use one and how the amount is set
4. ISF bonds: the standalone ISF single transaction bond
5. Who can sell a customs bond
6. Bond insufficiency notices: causes and consequences
7. What importers should do
8. Key references

A customs bond is a three-party financial instrument among an importer (the principal), a surety company, and CBP. It guarantees that the importer will pay all duties, taxes, and fees owed and will comply with CBP and other agency requirements. Without a valid bond on file, CBP will not release a formal entry. The three bond types most importers encounter are the continuous bond, the single transaction bond, and the ISF single transaction bond, each governed by 19 CFR Part 113.

The links in this article go to the primary documents: the regulations, official CBP pages, and the Treasury surety list themselves. Read the source.

What a customs bond is and why CBP requires one

CBP requires a bond on every formal import entry, on every Importer Security Filing, and on a range of other regulated activities such as operating a bonded warehouse or acting as a freight forwarder. The bond is not insurance for the importer; it protects the government. If the importer fails to pay duties or comply with an order, CBP calls on the surety to pay, and the surety then pursues the importer for reimbursement.

The legal framework for customs bonds sits in 19 CFR Part 113. That part sets out the different activity codes for bond types, the standard conditions each bond must satisfy, and CBP's authority to review and adjust bond amounts. The core conditions for the basic importation and entry bond appear at 19 CFR 113.62, and they include the obligation to pay all duties, taxes, and charges; to redeliver merchandise on demand; and to comply with all laws and regulations governing the imported merchandise.

Continuous bonds: how they work, coverage, and amount

A continuous bond is the standard choice for any importer who makes more than a handful of entries per year. Once filed and accepted by CBP, the bond remains in force until the principal or the surety formally terminates it, with written notice required. The premium is billed annually by the surety.

What a continuous bond covers

A single continuous bond covers every formal entry the importer makes at every U.S. port of entry during its term. It also satisfies the bond requirement for every Importer Security Filing tied to those entries. The importer does not need a separate bond instrument for each shipment.

How CBP sets the continuous bond amount

CBP uses a bond formula anchored in 19 CFR Part 113. The general rule is that the bond amount must equal 10 percent of the duties, taxes, and fees paid by the importer in the previous twelve months. The minimum bond amount is $50,000 regardless of the importer's actual duty payments. CBP rounds the calculated amount up to the next $10,000 increment.

CBP periodically reviews continuous bonds for sufficiency. If an importer's duty payments grow significantly, CBP may determine the existing bond amount no longer covers the exposure and issue a bond insufficiency notice (discussed below).

Importers bringing in merchandise subject to elevated tariff rates, including Section 301 or Section 232 duties, often find that their bond amount must be meaningfully higher than their historical twelve-month calculation because the new duty exposure rises faster than the bond is reviewed. Monitoring your effective duty rate relative to your bond amount is a practical ongoing task.

Single transaction bonds: when to use one and how the amount is set

A single transaction bond (sometimes called a STB or a one-time bond) covers exactly one entry at one port. It is consumed by that transaction and provides no coverage for any other shipment.

When a single transaction bond makes sense

• Occasional importers who make only one or two entries per year and whose annual duty payments would result in a continuous bond premium higher than the cost of buying individual STBs.
• Importers testing a new commodity or supplier before committing to regular imports.
• Situations where a continuous bond is temporarily insufficient and the importer needs to move a specific shipment while the bond is being increased.

How the single transaction bond amount is set

For a standard entry, the STB amount equals the entered value of the merchandise plus estimated duties, taxes, and fees. CBP sets the amount higher when the shipment involves merchandise subject to other agency requirements (for example, FDA, EPA, or USDA oversight) or merchandise subject to a tariff-rate quota. In those cases, the bond amount must be sufficient to cover potential liability if the merchandise cannot be admitted or must be redelivered.

ISF bonds: the standalone ISF single transaction bond

The Importer Security Filing requirement applies to ocean cargo destined for the United States. Importers with an active continuous bond satisfy the ISF bond requirement automatically. When an importer does not have a continuous bond on file, a standalone ISF single transaction bond is available to cover the ISF obligation for one shipment.

The ISF bond is not an entry bond. It does not allow goods to be released from CBP custody; a separate entry bond is still required at the time of formal entry. The ISF bond solely guarantees compliance with the ISF filing obligation and any liquidated damages that could arise from a late or inaccurate filing.

For a practical look at the ISF filing timeline and what triggers penalties, see our article on the ISF filing deadline, the 24-hour rule, and late filing consequences.

Who can sell a customs bond

Only a surety company holding a certificate of authority from the U.S. Department of the Treasury may write a customs bond. The Treasury publishes and regularly updates its Circular 570, which lists all companies currently certified to act as sureties on federal bonds, along with the maximum underwriting limit for each company.

In practice, most importers obtain their bond through their licensed customs broker, who works with a surety or a surety agent on the importer's behalf. The broker is not the surety; the broker arranges the bond. The importer is always the principal and remains liable even if the broker facilitated the paperwork.

When selecting a surety, verify that the company appears on the current Circular 570 list and that its underwriting limit is sufficient for the bond amount you need. CBP will not accept a bond from a surety that is not on the current list or that has exceeded its underwriting capacity.

Bond insufficiency notices: causes and consequences

CBP monitors whether existing continuous bonds remain adequate for the importer's actual duty exposure. When CBP concludes that a bond is no longer sufficient, it issues a formal bond insufficiency notice to the importer and the surety.

Common causes of bond insufficiency

• A significant increase in import volume or entered value since the bond was last set.
• New or increased duty rates on the importer's products, such as additional tariffs that raise the effective duty rate well above the historical baseline.
• CBP conducting a periodic review and finding the current bond amount below the 10-percent-of-duties formula.
• An outstanding unpaid duty bill or open compliance issue that increases the government's exposure.

What happens after the notice

Once CBP issues a bond insufficiency notice, the importer must either file a rider increasing the continuous bond amount or replace the bond with a new, higher-amount bond. Until CBP accepts and processes the increased bond, new entries may be held at the port. The surety must countersign any bond increase rider, and processing takes time, so acting immediately on a bond insufficiency notice is critical to avoiding entry delays.

If the importer cannot increase the continuous bond quickly enough to move an urgent shipment, a single transaction bond at the appropriate amount for that specific entry is one short-term option while the continuous bond is being corrected.

What importers should do

• Calculate your bond exposure annually. Pull your total duties, taxes, and fees paid in the past twelve months from your ACE data, apply the 10-percent formula, and compare the result to your current bond amount. If tariff rates on your products have changed recently, recalculate using the current effective rates rather than historical payments alone.
• Verify your surety's Circular 570 status. Confirm before each annual renewal that your surety remains on Treasury's current Circular 570 list and that your bond amount does not exceed the surety's underwriting limit.
• Act immediately on bond insufficiency notices. Contact your broker and surety the same day you receive a notice; processing a bond rider or replacement bond takes time, and entries will be held in the interim.
• Use single transaction bonds selectively. For occasional shipments or urgent entries during a bond gap, confirm the STB amount with your broker before filing; underestimating the amount on a quota or multi-agency shipment can expose you to liability.

Key references

• 19 CFR Part 113: CBP customs bonds regulation, covering all activity codes, bond conditions, and the continuous bond framework.
• 19 CFR 113.62: Standard conditions for the basic importation and entry bond.
• Treasury Circular 570: Current list of companies certified to act as federal bond sureties, with underwriting limits.
• CBP Bonds Program page: CBP's overview of bond requirements, bond sufficiency, and related guidance.
• 19 CFR Part 149: Importer Security Filing regulation, establishing the ISF bond requirement for ocean cargo.