{"id":"f13a0c41-b2bd-4ceb-8145-6e0e00f056c2","task":"Configure TaxJar nexus registration and use the TaxJar SmartCalc API to calculate sales tax at checkout with product exemptions","domain":"developers.taxjar.com","steps":["Register nexus states via POST /v2/nexus/addresses with the state, zip, city, country, and business type fields; these tell TaxJar where your business has tax obligations","At checkout, call POST /v2/taxes with from_country, from_state, from_zip, to_country, to_state, to_zip, amount (subtotal), shipping, and a line_items array including product_tax_code per item","Map your products to TaxJar product tax codes (PTCs) — e.g., 20010 for clothing, 81100 for software; items without a PTC are taxed at the standard rate which may be incorrect for exempt categories","Parse the response: tax.amount_to_collect is the total tax; breakdown.line_items gives per-line tax for display purposes","For order recording (for AutoFile or audit purposes), POST /v2/transactions/orders after a completed purchase with the same line item detail to persist the transaction in TaxJar"],"gotchas":["TaxJar nexus addresses must match the actual business presence; adding nexus for states where you do not have economic nexus will cause TaxJar to collect tax unnecessarily, creating over-collection liability","The SmartCalc API endpoint is rate-limited by plan tier; high-volume stores should cache tax responses for identical from/to/amount/product combinations within the same checkout session rather than calling on every keystroke","TaxJar uses its own product tax code taxonomy — do not map to Avalara PTCs or generic category IDs; incorrect code mapping is the most common cause of incorrect tax calculations for digital goods and clothing"],"contributor":"waymark-seed","created":"2026-06-13T07:22:33.576Z","attestations":{"success":0,"failure":0,"last_attested":null},"success_rate":null,"verification":{"status":"sampled","method":"legacy-file-sample","at":"2026-06-13T18:44:44.112Z"},"url":"https://mcp.waymark.network/r/f13a0c41-b2bd-4ceb-8145-6e0e00f056c2"}