What happens if I go over my limit?
Free tier hits a hard cutoff — upgrade to keep going. Paid tiers allow continued usage with overage billing at the end of the cycle.
Can I switch plans?
Yes. Upgrade or downgrade anytime. Changes take effect on your next billing cycle.
Do I need a credit card for Free?
No. Sign up with just an email and get your API key instantly.
What counts as an API call?
Each request to /calculate, /verify, or /nexus counts as one call. Rate lookups (/rates) and health checks are free and unlimited.
Can I use both products?
Yes. We offer the Sales Tax Engine and Capital Gains Tracker separately or bundled at a discount. Check out our Bundle Pricing for combined plans.
How do I know which of my agent's transactions are taxable?
Taxability depends on the work type, the buyer’s state, and where your agent has nexus — it is a classification question, not a single rate. Our
Agent Tax Compliance reference walks through how each determination is made.
How fast is a tax determination, and does speed cost extra?
Speed is not a pricing tier. Every plan, including Free, hits the same determination endpoint with the same engine — there is no premium latency tier to buy and no throttled tier to avoid. Plans differ in how many calls are included per month, not in how quickly a call returns.
What latency do you actually measure?
Our most recent measurement, on 2026-09-22, was a median of 164 ms and a 90th percentile of 228 ms across 12 sequential calls, fastest 148 ms and slowest 476 ms. The median is under 200 ms and the 90th percentile is not. That is an end-to-end round trip measured from a GitHub Actions runner, so it includes TLS setup, network transit and our own processing. It is a measurement of what we observed, not a service level agreement, and we do not publish one. Your own numbers will depend on where your agent runs; the method, and a one-minute loop that measures any vendor the same way, are in our
tax vendor comparison.
Do I pay per transaction or per determination?
Per determination. One call to /calculate is one unit against your monthly allowance, whether the result is taxable or exempt, and whether the amount is one dollar or ten thousand. A transaction you never ask us about costs nothing, and a transaction you ask about twice costs two.
Is there a minimum, an annual commitment, or a platform fee?
No. Plans are month to month, there is no seat charge, no onboarding fee and no separate charge for the nexus monitoring or the audit trail — those are part of every plan rather than add-ons. Enterprise is the one plan quoted individually, because its volume and terms are negotiated.