Authenticate to the Avalara REST v2 API using HTTP Basic Authentication with your account number and license key encoded in Base64.
Call the ListCrossBorderSections definition endpoint to retrieve the current list of restriction categories supported by the API (e.g., prohibited goods, quota items, items requiring import licenses).
For each product at checkout, POST a restriction check request with the destination country, HS code, and declared value; parse the response for restriction flags and any required documentation.
If a restriction flag is returned, surface a clear message to the shopper before completing the order; for license-required items, collect the importer license number or redirect the shopper to a compliance workflow.
Combine the restriction check with the landedCost calculation in a single checkout flow; perform restriction screening first to avoid calculating duties for a shipment that will ultimately be blocked.
Log all restriction check responses per order for compliance audit purposes; regulators may request evidence that restricted item screening was performed at point of sale.
Known gotchas
Avalara restriction data is sourced from tariff schedules and trade databases that are updated periodically but may not reflect last-minute regulatory changes; for high-risk product categories, supplement with legal counsel review.
A no-restriction API response is not a guarantee of customs clearance; local regulations, embargoes, and end-user screening (OFAC, denied parties) are separate compliance layers not covered by this API.
Restriction checks must be performed per destination country per product; a product that is unrestricted in one country may be prohibited in another — do not cache restriction results across different destination countries.
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