Goods usually leave the port before the final duty is determined. A surety bond is what makes that possible, guaranteeing the government will be paid whatever is eventually owed.
Why release precedes final assessment
Holding every shipment until classification, valuation and duty calculation were finalized would congest ports and delay commerce enormously.
Customs systems therefore allow release against a declaration, with the final assessment completed afterward and adjustments made if the declaration proves wrong.
That leaves a period where goods are in commerce and the debt is unsettled, which is the exposure the bond addresses.
How a three-party guarantee works
A customs bond involves the importer, a surety company, and the government. The surety promises to pay if the importer does not.
This is a guarantee rather than insurance. If the surety pays a claim, it seeks reimbursement from the importer, who remains ultimately liable.
The surety therefore underwrites the importer's finances much as a lender would, and may require collateral or a personal guarantee from a small business.
Single-entry versus continuous cover
A single-entry bond covers one shipment and is sized to that shipment's value and duties. It suits occasional importers.
A continuous bond covers all entries over a period and is sized by reference to duties, taxes and fees paid over the prior year, subject to a minimum.
Regular importers use continuous bonds because the per-shipment cost is far lower and because they avoid arranging cover for each arrival.
What the bond actually covers
The obligation extends beyond duty. It covers taxes, fees, penalties for regulatory breaches, and the importer's compliance with entry requirements generally.
That is why a bond can be called on for reasons unrelated to unpaid money, such as failure to redeliver goods that another agency has refused admission.
Additional duties assessed long after entry, following a later determination, also fall within the bond's period, which can create exposure years after a shipment cleared.
Why bond amounts get reviewed
If an importer's duty liability rises sharply, the existing bond can become insufficient, and shipments may be held until the amount is increased.
Sureties monitor this because their exposure grows with the importer's volumes, and they may require additional security before agreeing to a larger bond.
Importers whose duty costs change materially generally review bond sufficiency in advance, since discovering the problem at the port means cargo sitting while it is fixed.