Calculate sales tax for a transaction using TaxJar
domain: taxjar.com · 5 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Authenticate with your TaxJar API token in the Authorization header as 'Token token=<API_KEY>'
POST to https://api.taxjar.com/v2/taxes with a JSON body containing 'from_country', 'from_zip', 'from_state', 'to_country', 'to_zip', 'to_state', 'amount', and 'shipping'
Include a 'line_items' array with 'id', 'quantity', 'unit_price', and optionally 'product_tax_code' for each item to get per-line breakdowns
Read 'tax.amount_to_collect' from the response for the total tax due and 'tax.breakdown' for jurisdiction-level detail
Store the returned 'tax.rate' and jurisdiction data alongside the order record for audit purposes
Known gotchas
Omitting 'product_tax_code' causes TaxJar to default to fully taxable tangible personal property; digital goods, groceries, and clothing may have different rates
Sandbox and production use different base URLs (api.sandbox.taxjar.com vs api.taxjar.com); sandbox tokens do not work on production
TaxJar returns 0 tax for transactions where the seller has no nexus in the destination state, even if the buyer's state has a tax; always separately track your nexus registrations
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