AvaTax calculates sales tax by using address-based sourcing, jurisdiction-level tax rules, product tax codes, and customer exemption status to determine the correct tax amount for each transaction. This article explains the calculation process AvaTax follows when you create a sales transaction in AvaTax or through an integrated system like Microsoft Dynamics NAV, Dynamics 365 Business Central, or SAP S/4HANA Public Cloud.
By the end of this article, you will understand the steps AvaTax follows to calculate tax, what information it uses, and how it returns tax amounts to your transaction.
Quick answer
AvaTax calculates tax by looking up tax jurisdictions based on transaction addresses, applying jurisdiction-level rates and rules, and factoring in product tax codes and customer exemptions.
The system returns calculated tax amounts for each jurisdiction level: state, county, city, and special districts.
AvaTax automatically calculates sales tax or use tax depending on the transaction type and does not calculate tax for customers marked as exempt.
Tax calculations appear in your transaction as soon as you complete the required fields and trigger the AvaTax request.
What information AvaTax uses to calculate tax
AvaTax determines the tax amount by analyzing several transaction details you provide:
Address data: AvaTax uses the ship-to address to identify the correct tax jurisdictions. The system looks up jurisdiction codes based on ZIP Code, City, County, and State. Address accuracy directly affects which jurisdictions and rates apply.
Transaction details: The calculation request includes item quantities, unit prices, tax types, freight amounts, and jurisdiction codes. AvaTax uses these details to apply the correct rates and rules.
Tax code mappings: Map your products and services to Avalara tax codes. These mappings tell AvaTax which tax rules apply to each item.
Exemption indicators: AvaTax checks whether the customer is marked as exempt and applies the corresponding exemption codes. The system does not calculate tax for exempt customers.
Document type: AvaTax calculates sales tax for sales transactions and consumer use tax for purchase transactions. The calculation logic adjusts based on the document type.
How AvaTax calculates tax step by step
When you create a transaction in AvaTax or an integrated system, the calculation follows this process:
Tax jurisdiction lookup
The system retrieves jurisdiction codes based on the transaction address. In integrated systems like SAP S/4HANA Public Cloud, the connector triggers the tax jurisdiction lookup service to match the address data to state, county, city, and special district codes.
Tax calculation request
Your system sends the transaction details to AvaTax. This request includes all the information AvaTax needs: item quantities, tax types, exemption indicators, freight amounts, and the jurisdiction codes from the previous step.
AvaTax calculation logic
AvaTax determines taxability, rates, exemptions, and special tax types by using jurisdiction-level rules. The system applies the correct rate for each jurisdiction that has taxing authority over the transaction address.
AvaTax also handles freight charges, applies customer-specific exemptions, and supports both origin and destination sourcing models depending on state rules.
Multilevel tax determination
AvaTax calculates tax separately for each jurisdiction level: state, county, city, and special districts. The system returns the tax amount for each level so you can see the full breakdown.
Response and transaction update
AvaTax sends the calculated tax amounts back to your system. In integrated platforms, the connector reformats the AvaTax response into a compatible structure and updates the original transaction with the tax amounts.
Calculating tax for a sales transaction in Dynamics 365 Business Central
If you use Avalara for Dynamics 365 Business Central, follow these steps to calculate tax for a sales invoice:
- From Microsoft Dynamics 365 Business Central Home, go to Sales > Sales Invoices.
- Select New to create a new invoice.
- In the Customer field, select the customer you are selling to.
- Confirm or enter the Posting Date and Document Date.
- In the Lines section, enter the items or services:
- In the Type field, select Item or Resource.
- In the No. field, select the item or resource.
- Enter the Quantity and Unit Price.
- Ensure that the Tax Area Code is AVATAX and the Tax Group Code is Taxable or NT.
- Confirm that the Ship-to Address is correct.
- Select Statistics and review the tax in the Tax Amount field.
The system calculates tax using AvaTax as soon as you complete the required fields. The Tax Amount field shows the calculated tax for your transaction.
Calculating tax in Microsoft Dynamics NAV
For Avalara for Microsoft Dynamics NAV users, enable tax calculation for your company and set AvaTax as the tax calculation method in your application settings.
Map your products and services to Avalara tax codes to apply the correct tax rules, and ensure that you mark exempt customers with the correct exemption codes. When these settings are in place, AvaTax automatically calculates the applicable sales or use tax for each transaction.
How AvaTax handles tax-exempt transactions
AvaTax does not calculate tax for customers marked as exempt. When you create a transaction for an exempt customer, the system checks the exemption indicator and applies the exemption code. The calculated tax amount returns as zero.
Tax-exempt sales are still included in AvaTax's economic nexus threshold calculations by default. This aligns with how most states define thresholds by gross sales or total revenue.
What AvaTax does when you do not override tax
If you enter a transaction without a tax override, AvaTax automatically calculates the appropriate tax. For purchase documents, AvaTax calculates consumer use tax, including both the accrued tax and vendor tax paid. These two values are expected to match.
If you use Managed Returns, the calculated tax is used automatically on your returns. To credit a previously calculated or reported accrual, enter a negative cost amount.
How sales totals are calculated for threshold determinations
AvaTax calculates sales totals as the total of all committed sales invoices minus return credits. However, some states use gross sales for their calculations. Review state-specific rules to ensure your threshold monitoring aligns with each state's requirements.
Expert tip: Review calculation details to troubleshoot unexpected tax
If the calculated tax amount doesn't match your expectations, go to Transactions in AvaTax, select the transaction, click the arrow next to a line item, and select Review This Calculation to see the detailed breakdown of rates and jurisdictions applied. This shows you specific tax rates and provides troubleshooting advice based on why the calculation might differ from what you expected.
How Galvix can help with sales tax calculations and filing
AvaTax automates sales tax calculations, but your finance team still needs to ensure that transaction data, product tax codes, customer exemptions, and tax amounts are accurate.
If your team is spending too much time reviewing tax calculations, reconciling transactions, and preparing returns, Galvix can take that ongoing compliance work off their plate. Our team works with data from your billing and accounting systems, reconciles sales and tax amounts, prepares sales tax returns, and files them after your approval. You can track everything through a dashboard without managing the filing process yourself.
Book a demo to see how Galvix can help manage your sales tax compliance.
FAQ
Does AvaTax calculate tax for every transaction automatically?
Yes, once you enable AvaTax and set it as the tax calculation method, it calculates tax automatically for each transaction based on the address, tax codes, and exemption status you provide. You do not need to manually trigger the calculation.
Can I see the tax breakdown by jurisdiction level?
Yes, AvaTax returns tax amounts for each jurisdiction level: state, county, city, and special districts. The breakdown appears in your transaction details depending on your system's interface.
What happens if the ship-to address is incomplete?
If the address data is incomplete or inaccurate, AvaTax may not identify the correct jurisdictions, which can result in incorrect tax amounts. Always confirm that the ship-to address includes a valid ZIP Code, City, County, and State.
Does AvaTax calculate tax on freight charges?
Yes, AvaTax calculates tax on freight charges when applicable based on the jurisdiction rules and the taxability of freight in the transaction's destination state.
How does AvaTax handle tax overrides?
If you enter a tax override on a transaction, AvaTax uses the override value instead of calculating tax automatically. This is useful for correcting previously calculated or reported accruals, but you should use overrides carefully to maintain compliance.
