# Taxability of single article surtax across multiple invoices in Florida

Source: https://developer.avalara.com/sales-tax-integration-guide/zvn4285772624204/

# Taxability of single article surtax across multiple invoices in Florida

Learn how AvaTax calculates Florida single article surtax across multiple invoices for a single purchase, and how to use purchase order numbers to link related transactions.

In Florida, local discretionary sales surtax applies to the first $5,000 of a single item or sale of tangible personal property. If a large purchase, such as a boat, modular structure, or heavy equipment, is delivered or invoiced in stages across multiple purchase orders or invoices, AvaTax must evaluate the single article threshold across the entire purchase. It doesn't reset the threshold for each individual invoice.

To make sure AvaTax accumulates the $5,000 single article surtax threshold across multiple invoices, pass the same purchase order number in the `purchaseOrderNo` field on each related `CreateTransaction` request.

-   **Threshold accumulation:** AvaTax uses the `purchaseOrderNo` value to identify separate invoices that belong to the same single article purchase. It tracks the cumulative taxable amount across transactions that share that PO number until the $5,000 surtax threshold is reached.

-   **Surtax cutoff:** After the cumulative amount for items tied to that PO number exceeds $5,000, AvaTax stops calculating Florida discretionary sales surtax on later invoice lines tied to that PO number. It applies only the standard state sales tax rate to the remaining amount.

-   **Consistent mapping:** Make sure all partial delivery or milestone invoices for the same purchase include the exact same PO number in the `purchaseOrderNo` field.

Important

This multi-invoice PO number behavior is specific to Florida's single article discretionary sales surtax. Tennessee also has a single article tax, but Tennessee calculates it for each item on a per-transaction basis. It doesn't accumulate thresholds across multiple invoices by using PO numbers.

To support Florida multi-invoice single article surtax transactions in your integration:

-   **Capture the PO number:** Make sure your checkout, order management, or ERP system captures the customer's purchase order number and passes it in the `purchaseOrderNo` attribute at the transaction header or line level.

-   **Preserve the PO number across billing milestones:** When you split a sales order or contract into multiple invoices, carry the original `purchaseOrderNo` to all resulting invoice transactions sent to AvaTax.

-   **Commit transactions in sequence:** Commit each transaction in AvaTax when you invoice it so that later invoices can reference the accumulated surtax amount applied to earlier billing lines.