How do I connect Avalara to calculate tax on AR invoices?

Loopfour's Avalara integration creates AvaTax transactions scoped to sales-side document types — SalesInvoice or SalesOrder — each requiring a unique document code and a customerCode identifying the buyer. Avalara calculates tax against the line items you send and returns totalTax and grandTotal, which downstream steps use to invoice or charge the customer.

By Zuny Fester, Head of Operations and Marketing

Reviewed by Zuny Fester

Published September 14, 2026Last reviewed September 14, 2026Editorial policy

Part of the finance integrations guide.

Document types supported	SalesInvoice, SalesOrder only, per Loopfour's integration schema
Required fields	documentType, customerCode, a unique document code, and line items
What Avalara returns	totalTax (calculated tax) and grandTotal (totalAmount + totalTax)
Not exposed here	AvaTax's own API also supports PurchaseInvoice/PurchaseOrder — Loopfour's schema doesn't currently use them

What Loopfour's Avalara integration actually creates

Every AR-side tax calculation through Loopfour's Avalara integration goes through the same underlying call: creating an AvaTax transaction with documentType set to SalesInvoice or SalesOrder. Avalara's full API supports a much longer list of document types — sales, purchase, return, inventory-transfer, reverse-charge, and customs variants — but Loopfour's integration schema (avalaraDocumentTypeSchema) only accepts the two sales-side values. That's a scoping decision in Loopfour's code, not a limit of AvaTax itself.

Setting it up

Each transaction needs a document code that's unique within its company and document type — reused codes against a committed transaction return a DocumentCodeConflict error rather than creating a new record. It also needs a customerCode identifying the buyer, and at least one line item describing what's being sold, since tax is calculated per line based on the product/service and the ship-to address.

What you get back

A successful call returns totalTax (the calculated tax amount) separately from totalAmount (the pre-tax line total), plus grandTotal, which is the two added together — the number that should match what the customer is actually invoiced or charged. By default the transaction is created but not committed; committing it is what makes it count toward tax-liability reporting.

Next step

Map the finance workflow with the most exposure and prove the automation path.

Bring the invoice, contract, payment reconciliation, or customer finance workflow you have to defend at audit. Loopfour can map the trigger, controls, integrations, and approval loop.

Book a workflow review

Field mapping

Fields Loopfour sends to and receives from AvaTax for an AR invoice

Field	Direction	Purpose
documentType	Sent	SalesInvoice or SalesOrder — the only two values Loopfour's schema accepts
code	Sent	Unique document code — reused against a committed transaction fails with DocumentCodeConflict
customerCode	Sent	Identifies the buyer for tax jurisdiction and exemption purposes
totalTax	Returned	Calculated tax, separate from the pre-tax amount
grandTotal	Returned	totalAmount + totalTax — what the customer should actually be charged

Frequently Asked Questions

Not currently — Loopfour's integration schema restricts documentType to SalesInvoice and SalesOrder, even though AvaTax's own API supports PurchaseInvoice and PurchaseOrder for the buy side.

If the original transaction was already committed, AvaTax returns a DocumentCodeConflict error rather than overwriting it. If it was never committed, sending the same code again updates that transaction instead of creating a new one.

No — an uncommitted transaction still returns a real totalTax figure you can charge against, but it won't count toward tax-liability reporting until it's explicitly committed.

Sources

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AR & Collections

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Diagnostic

Why is Avalara rejecting a sales invoice with a DocumentCodeConflict error?

A DocumentCodeConflict means the document code you sent already belongs to a committed transaction in AvaTax. The fix is not a fresh code — retrying with a new code every time is exactly what creates duplicate tax transactions on a real network retry. Keep the code stable, derived from the source invoice, and call the adjust or void endpoint if the original genuinely needs to change.

Diagnostic

Why doesn't an uncommitted Avalara transaction show up on my sales tax return?

AvaTax only reports committed transactions. Commit status is a flag that determines whether a transaction appears on your compliance reports and gets remitted — uncommitted transactions are treated as provisional and are excluded from liability calculations and filings until someone explicitly commits them.