Avalara AvaTax API
✓ Official Vendor SpecFinanceTaxbasic432 EndpointsREST
For Agents
Calculate sales tax and VAT on transactions, manage exemption certificates, and file returns across thousands of US and international tax jurisdictions.
Use for: I want to calculate sales tax on a $250 order shipping to California, Commit a sales transaction so it appears on the next return filing, Void a transaction that was cancelled by the customer, Look up nexus jurisdictions where my company collects tax
Not supported: Does not handle payment capture, accounting ledgers, or customer-facing invoicing — use for tax calculation, exemption management, and returns preparation only.
The Avalara AvaTax API is a REST interface to Avalara's enterprise tax engine for calculating sales, use, VAT, and GST on transactions across US and international jurisdictions. It manages companies, locations, nexus declarations, exemption certificates, returns filing, and audit trails alongside real-time transaction calculation. Authentication uses HTTP Basic with an account ID and license key, and the spec exposes 432 operations across 314 paths, including a sandbox at sandbox-rest.avatax.com.
Install Jentic One Beta
Connect the AvaTax API to your agent
Jentic One is a self-hosted execution layer for AI agents. It lets your agent call the AvaTax API, or any other public or private API you need. You set the rules, the agent never sees your credentials, and every call is logged.
Two steps, two machines. Install the instance in a safe environment, then register your agent from wherever it runs.
1
Step 1: Jentic One Host machine
# On the machine that will host your Jentic One instance:
curl -fsSL https://raw.githubusercontent.com/jentic/jentic-one/main/tools/install.sh | sh2
Step 2: Agent machine
# On the machine where your agent runs (keep this separate from the instance):
curl -fsSL https://raw.githubusercontent.com/jentic/jentic-one/main/tools/install.sh | sh
jentic register # connects your agent to your Jentic One instanceJentic One is in public beta. The setup above keeps your agent separate from the instance, which is what you want before using real credentials: an agent running as the same OS user as Jentic One can read its stored keys directly. Just evaluating? A single local install is fine to start. See the secure deployment guide for the tiers.
Capabilities
What an agent can do with AvaTax API.
Calculate transaction tax in real time across US sales tax, EU VAT, and GST jurisdictions via /api/v2/transactions/create
Commit, void, or adjust posted transactions to keep tax records aligned with the source ERP
Manage company nexus declarations, locations, and tax codes through /api/v2/companies endpoints
Validate and store exemption certificates against customer records for audit-ready exempt sales
Generate jurisdiction-level liability reports and prepare returns for filing through Avalara Returns
Use Cases
Patterns agents use AvaTax API for, with concrete tasks.
★ Real-Time Checkout Tax Calculation
E-commerce platforms call Avalara AvaTax at checkout to calculate jurisdiction-accurate sales tax, VAT, or GST on the order line items based on ship-to address, product taxability codes, and customer exemption status. AvaTax handles the 13,000+ US sales-tax jurisdictions plus international rules, replacing static rate tables that go stale within weeks.
POST /api/v2/transactions/create with type=SalesInvoice, customer code, ship-from and ship-to addresses, and line items, then return totalTax and per-line jurisdiction breakdown
Exemption Certificate Management
B2B and wholesale sellers use AvaTax to collect, validate, and apply customer exemption certificates so qualifying transactions are correctly tax-exempt and audit defensible. Certificates are linked to customers and shipping jurisdictions through the customers and certificates endpoints, removing the spreadsheet and PDF folder workflow.
Create a customer record under company {id}, attach an exemption certificate for the resale category in Texas, and confirm subsequent transactions for that customer in TX return zero tax
Returns Preparation and Filing
Finance teams use AvaTax to commit transactions throughout the period and then generate jurisdiction-level liability reports as the basis for sales and use tax returns. Committed transactions roll up into worksheets that feed Avalara Returns or the team's chosen filing process, replacing manual reconciliation across dozens of state portals.
List committed transactions for company {id} between 2026-05-01 and 2026-05-31, group totalTax by jurisdiction, and produce a state-by-state summary
Nexus and Address Validation
Growing sellers track economic and physical nexus across states using AvaTax nexus declarations and address-validation utilities. The API surfaces where the company is registered to collect tax and validates addresses to tax-jurisdiction precision before transactions are committed.
List active nexus jurisdictions for company {id} and flag any state where the most recent 12 months of transactions exceed the economic nexus threshold but no nexus is declared
Agent-Driven Tax Compliance via Jentic
AI agents embedded in finance and operations workflows call AvaTax through Jentic to answer ad-hoc tax questions, classify products to tax codes, and trigger transaction adjustments without engineers wiring custom integrations. Jentic exposes the 432 AvaTax operations as searchable tools so agents pick the right one by intent.
Given a product description, search Jentic for 'look up tax code', call AvaTax to find the closest matching tax code, and write it back to the product master
Key Endpoints
432 endpoints — the avalara avatax api is a rest interface to avalara's enterprise tax engine for calculating sales, use, vat, and gst on transactions across us and international jurisdictions.
METHOD
PATH
DESCRIPTION
POST
/api/v2/transactions/create
Create a tax transaction for a sale or invoice
GET
/api/v2/companies
List companies under the account
GET
/api/v2/accounts/{id}
Retrieve account details
POST
/api/v2/addresses/resolve
Resolve an address to taxing jurisdictions
GET
/api/v2/definitions/taxcodes
List available tax codes for product classification
POST
/api/v2/companies/{companyId}/customers
Create a customer under a company
POST
/api/v2/transactions/create
Create a tax transaction for a sale or invoice
GET
/api/v2/companies
List companies under the account
GET
/api/v2/accounts/{id}
Retrieve account details
POST
/api/v2/addresses/resolve
Resolve an address to taxing jurisdictions
GET
/api/v2/definitions/taxcodes
List available tax codes for product classification
POST
/api/v2/companies/{companyId}/customers
Create a customer under a company
Why Jentic?
Three things that make agents converge on Jentic-routed access.
Credential isolation
Avalara account IDs and license keys are stored encrypted in the Jentic vault. Agents call AvaTax through Jentic with scoped tokens — the raw HTTP Basic credentials never enter the agent's context or logs.
Intent-based discovery
Agents search by intent (e.g., 'calculate sales tax for an order') and Jentic returns the matching AvaTax operation from the 432 available, with the full request schema for transaction lines, addresses, and tax overrides.
Time to first call
Direct AvaTax integration: 1-2 weeks for auth, transaction mapping, address resolution, and exemption flows. Through Jentic: under 1 hour — search, load schema, execute.
Related APIs
Alternatives and complements available in the Jentic catalogue.
Complementary
Stripe
Pair Stripe Payments with AvaTax to calculate jurisdiction-accurate tax on charges and invoices.
Use Stripe for payment capture and AvaTax for tax determination when checkout requires both.
FAQs
Specific to using AvaTax API through Jentic.
What authentication does the AvaTax API use?
AvaTax uses HTTP Basic authentication with the account ID as the username and a license key as the password. Through Jentic, the account ID and license key live in the Jentic vault — agents receive scoped access rather than the raw license key.
Can I calculate tax for international transactions with the AvaTax API?
Yes. POST /api/v2/transactions/create supports VAT, GST, and country-specific consumption taxes when the ship-from and ship-to addresses are international and the company has the relevant nexus configured. The same endpoint handles US sales tax.
What are the rate limits for the AvaTax API?
Avalara enforces per-account throttling that scales with subscription tier; production accounts typically allow several hundred transactions per second. Watch for HTTP 429 responses and respect the Retry-After header — heavy bulk loads should use the batch endpoints instead of single-transaction calls.
How do I commit a transaction through Jentic?
Search Jentic for 'commit a tax transaction', load the schema for the AvaTax commit operation under /api/v2/companies/{companyCode}/transactions/{transactionCode}/commit, and execute with commit=true. Committed transactions are immutable and roll into the next reporting period.
Is the AvaTax sandbox free to use?
Avalara provides a free sandbox at https://sandbox-rest.avatax.com for development and testing with separate sandbox credentials. Production calculation and returns filing are paid based on transaction volume and jurisdictions filed.
Can I look up a tax code for a product through the AvaTax API?
Yes. GET /api/v2/definitions/taxcodes returns the Avalara tax-code catalog, and the company-level tax-code endpoints let you map your SKUs to those codes so calculations apply the right taxability rules.
GET STARTED