POST tax calculation requests for checkout, billing, ERP, and finance workflows with line-level results.
Sales Tax Calculation API for Checkout, Billing, and ERP
Calculate sales tax in real time through an API designed to connect transaction-time decisions to the broader compliance workflow — not just a standalone rate lookup.
Prophit.ai supports API-driven sales tax calculation for checkout, billing, ERP, finance, and payment workflows, with jurisdiction sourcing, tax treatment logic, Developer Console access, and continuity into filing-ready outputs where configured.
Feed calculated decisions into review, reporting, period-close, and filing-ready workflows where configured.
Manage sandbox keys, monitor requests, and review usage through configured Developer Console workflows.
From transaction request to connected compliance context.
The Prophit.ai Sales Tax API is built for teams that need tax answers at transaction time and continuity into the compliance workflow downstream.
Send transaction data
Submit ship-to address, line items, tax codes, and transaction context through `/api/v1/tax/calculate` or `/api/v1/tax/quotes`.
POST /api/v1/tax/quotesSource jurisdiction
Apply jurisdiction logic from the transaction context with rate precision metadata in the response.
Apply tax treatment
Evaluate taxability, exemption context, and product treatment with line-level tax breakdown.
Return the quote
Receive calculated tax, combined rate, and jurisdiction breakdown for checkout or downstream posting.
Feed compliance workflow
Commit transactions where configured and connect results to review, reporting, and filing-ready outputs.
POST /api/v1/transactionsCheckout and finance systems need tax answers at transaction time.
Ecommerce checkout, billing platforms, ERP order flows, and payment systems all need sales tax calculated when the transaction happens — not after the period closes.
A sales tax API also needs to connect to the compliance workflow downstream: reconciliation, review, evidence, reporting, and filing-ready outputs where configured.
Transaction-time calculation
Support checkout, billing, and order workflows that need tax at the moment of sale.
Connected compliance context
Carry calculated decisions into review, reporting, and filing-ready workflows instead of isolating API output.
Beyond rate lookup
Support sourcing, treatment, exemption context, and line-level breakdown — not just a single rate answer.
Built for real-time calculation and connected tax operations.
Prophit.ai supports a US sales tax calculation API under `/api/v1` with stateless calculate/quote endpoints, transaction lifecycle support, API key authentication, and Developer Console visibility where enabled.
Real-time calculate and quote
Stateless `/api/v1/tax/calculate` and `/api/v1/tax/quotes` endpoints for line-level US sales tax results.
Jurisdiction sourcing and rates
Ship-to-driven jurisdiction logic with state, county, city, and special district breakdown in responses.
Tax treatment support
Nexus awareness, exemption certificate context, SKU/tax-code taxability, shipping rules, and tax-included backout where configured.
Transaction lifecycle
Commit, void, and refund transactions where configured with isolated sandbox and production namespaces.
API keys and Developer Console
Sandbox and live keys, request logs, usage summaries, and webhook subscriptions where enabled.
Environment-aware rate limits
60 sandbox requests per minute, a higher live tier, dedicated batch and experimental-estimate buckets, and clear retry guidance.
API calculation connects to the broader ITMS compliance platform.
The differentiator is not just returning a tax amount. Prophit.ai connects API-driven calculation to sales tax compliance, filing-ready workflows, and tax-professional-grade review downstream.
Sales tax software overview
See how sales and use tax workflows map to business complexity across modules and plans.
Explore sales tax softwareSales tax filing software
Connect calculated tax to filing-ready returns, reconciliation, and review workflows.
Explore filing softwareSales Tax Compliance module
Review transaction data, nexus, obligations, and filing-ready packages in one connected workflow.
Explore compliance moduleDeveloper Console, API keys, and request visibility.
Teams with configured API Access use the Developer Console to create sandbox keys, review requests, inspect usage summaries, and manage webhook subscriptions where enabled.
Technical reference documentation lives at `/api-access` — quickstart, authentication, environments, schemas, and sample requests.
- 01
Request or configure API Access for your Enterprise workspace where supported.
- 02
Create a sandbox API key in the Developer Console and review the one-time secret.
- 03
Send calculate or quote requests to `/api/v1/tax/quotes` with ship-to and line-item context.
- 04
Review line-level tax, rate breakdown, and jurisdiction metadata in the response.
- 05
Commit transactions where configured and monitor request logs in the Developer Console.
- 06
Connect committed data to compliance review, reporting, and filing-ready workflows.
API Access is an Enterprise capability, configured by contract.
API Access (Sales Tax Calculation API) is available on Enterprise plans by contract — not included in Starter or Professional self-serve plans.
Sandbox keys and Developer Console workflows are available once API Access is provisioned for your organization and location.
Self-serve core workflows
Core sales, purchasing, and exemption workflows without API Access provisioning.
API Access by contract
Configured API Access with sandbox keys, live access enablement, Developer Console, and enterprise controls where supported.
Isolated testing environment
Sandbox keys calculate against real rate logic while keeping sandbox transactions isolated from production filing workflows.
Built for teams that need tax at transaction time.
The Sales Tax API supports headless commerce, platform billing, ERP integrations, and enterprise tax calculation workflows where API Access is configured.
Ecommerce checkout
Calculate tax during checkout for carts, marketplaces, and custom storefronts.
Billing and subscriptions
Apply tax to invoices, renewals, and usage-based billing events at calculation time.
ERP and order workflows
Integrate tax calculation into order capture, invoicing, and finance posting flows.
Marketplace and platform operators
Support tax calculation across seller or location context where configured.
Finance period-close support
Connect transaction-time calculations to reconciliation and filing-ready review downstream.
Headless commerce
Embed tax calculation into custom checkout and payment experiences through API requests.
A rate lookup answers one question. A sales tax API should connect to compliance.
Rate lookup tools answer a narrow question. Prophit.ai is designed for teams that also need sourcing, treatment, evidence, reporting, and filing-ready continuity across the compliance workflow.
Rate lookup alone
Returns a rate or amount without connected review, reporting, or filing-ready workflow context.
Sales tax API + platform
Supports calculation at transaction time with downstream compliance, review, and filing-ready outputs where configured.
Tax-professional-grade workflow
Preserve request context, transaction history, and review paths instead of treating tax as a black-box side effect.
Common questions.
What is a sales tax API?
A sales tax API lets applications calculate sales tax programmatically at transaction time by sending address, line-item, and tax context to an endpoint and receiving calculated tax results in the response.
What is the difference between a sales tax API and sales tax software?
Sales tax software supports the broader compliance workflow — data ingest, review, reporting, exemptions, filing-ready outputs, and controls. A sales tax API focuses on programmatic calculation and transaction lifecycle support that connects into that workflow.
Can Prophit.ai calculate sales tax in real time?
Yes. Prophit.ai supports real-time sales tax calculation through `/api/v1/tax/calculate` and `/api/v1/tax/quotes` where API Access is configured for your workspace.
Does the API support filing workflows?
API calculation connects to the broader compliance platform. Committed production transactions can feed review, reporting, and filing-ready workflows where configured. Returns API capabilities require separate scopes and module enablement.
Is API access available in every plan?
No. API Access (Sales Tax Calculation API) is an Enterprise capability available by contract. It is not included in Starter or Professional self-serve plans.
Does Prophit.ai provide a sandbox?
Yes, where API Access is provisioned. Sandbox keys use isolated transaction namespaces for testing without affecting production filing workflows. Sandbox access is configured through Enterprise API Access setup.
Can the API connect to ERP, billing, ecommerce, or payment systems?
Yes. The API is designed for integration into ERP, billing, ecommerce checkout, finance, and payment workflows through standard HTTP requests and API key authentication where configured.
Does the API make final tax decisions automatically?
No. The API returns calculated results for integration into your workflow. Tax professionals retain review and approval over important tax decisions, reporting, and filing-ready outputs.
Connect real-time calculation to your sales tax workflow.
Explore API Access documentation, compare Enterprise plans, or talk with Prophit.ai about configured API workflows for your team.
- Production standalone Sales Tax and Use Tax Engines ($99/month per location through sales-assisted setup, with 10,000 calls/month included) return determinations to source systems through an API.
- The tax content is published and auditable: the Sales Tax Atlas carries 51 state and DC guides and 3,800+ county and city rate pages, each pinned to its official source.
- Flat pricing per organization: $199/month Starter and $599/month Professional, with no per-state, per-filing, or per-transaction fees — plus a published à-la-carte module menu.