Taxation determination is the calculation a business runs to figure out exactly how much sales tax, value-added tax (VAT), or goods and services tax (GST) applies to a given transaction. This calculation is based on what’s being sold, where the buyer is located, and whether either party qualifies for an exemption. A flat rate works when a business sells in one place, but the moment the business adds a state, a country, or a product category with its own rules, it’s no longer valid, since each of those additions changes which rate applies and whether it applies at all.

Below, we’ll go over how tax determination engines process a transaction, the specific inputs they check before deciding on a number, and why digital goods create more complexity than physical goods.

Key takeaways

• Tax determination depends on multiple factors, including product type, buyer location, and exemptions.

• Digital goods and physical goods often follow different rules in the same jurisdiction. For example, a state or country can tax a physical product while exempting or partially taxing its digital equivalent.

• Manual tax processes tend to fail once a business crosses new economic nexus thresholds, which makes a tax engine a beneficial tool.

What is taxation determination?

Taxation determination is the calculation you use to figure out exactly how much sales tax, VAT, or GST a buyer owes, and it depends on more than one rate. Product classification, buyer location, and exemption rules all have to align before you arrive at the correct number.

How does tax determination work?

Tax determination runs through the same basic sequence for each transaction. The process identifies where the sale is happening, what’s being sold, who’s buying it, and whether either party has already met an exemption or a registration threshold that changes the outcome. Here are the steps, in order.

1. Locate the transaction

The system captures the ship-from address, the ship-to address, and sometimes the billing address, since sourcing rules differ by state and country and can change which address sets the rate.

2. Classify the product

Each item is mapped to a tax code because clothing, groceries, digital goods, and software often carry different rates or exemptions.

3. Check registration status

The system confirms whether the seller has crossed a nexus threshold or holds an active registration in that jurisdiction. Tax should only be collected where the seller has a legal obligation.

4. Apply exemptions

Resale certificates, nonprofit status, or product-specific exceptions are checked against the transaction before a rate is applied.

5. Calculate and round

The final rate is a blend of state, county, city, and special district rates in the US. It’s applied and rounded according to that jurisdiction’s rules.

What factors do tax determination engines evaluate?

A tax determination engine is software that automates the calculation of indirect taxes such as sales tax, VAT, and GST by cross-referencing a set of inputs. Missing any one of them can produce the wrong number even when everything else checks out.

Here are the factors used by tax determination engines:

• Ship-to and ship-from addresses: This includes the ZIP+4 or postal code in the US, since city and district rates can change block to block.

• Product tax codes: These classify whether an item is a physical good, a digital download, a software-as-a-service (SaaS), or something exempt, such as certain food or medical items.

• Customer exemption certificates: These reduce or eliminate tax for resellers, nonprofits, or government buyers, provided the certificate is valid and on file.

• Tax registrations: These mark the states or countries where the business has already registered to collect tax, based on physical presence or economic activity.

• Marketplace facilitator status: In the US and several other countries, the marketplace itself, not the individual seller, is responsible for collecting and remitting tax.

• Rate and rule updates: Jurisdictions change rates, redraw boundaries, and revise product taxability on their own schedules, often many times a year.

How does tax determination differ for digital goods vs. physical goods?

US states generally tax tangible personal property by default, with specific exceptions for categories such as groceries or prescription drugs. Digital goods and software don’t follow that same logic, and the differences between jurisdictions add up quickly. This is true for SaaS subscription products, which is why a business selling the same subscription in three different states might need three different approaches. Digital downloads are split even further.

Keep these specifics in mind:

• Comparable product states: Some states tax ebooks and streaming video the same way they would tax a physical book or DVD, which means they treat the digital version as equivalent to its physical counterpart.

• Situations where there is no comparable product: Other states tax digital products only if a comparable physical version exists. This creates uncertainty for items that have no physical equivalent, such as downloadable in-game items.

• VAT on digital services: VAT and GST treatment tends to be more consistent, since countries generally apply VAT based on the buyer’s location for digital products, though the rate itself varies by country (from 17% to 27% across the EU alone).

Why does manual tax determination fail at scale?

Manual tax determination, such as a spreadsheet of rates or a handful of hardcoded tax percentages, works fine for a business that sells in one jurisdiction. Once growth adds jurisdictions, however, it can start to fail. Consider the following:

• Jurisdiction count: The US alone has more than 13,000 sales tax jurisdictions, and each sets its own rates.

• Economic nexus thresholds: Since the 2018 South Dakota v. Wayfair decision, US states can require out-of-state sellers to collect tax once they cross an economic nexus threshold, commonly $100,000 in sales or 200 transactions in a state, even without a physical presence there.

• Retroactive liability: A business that crosses that threshold in a new state but doesn’t register owes back taxes on every sale made after the threshold was hit, along with potential interest and penalties.

• International compounding: VAT and GST registration thresholds vary by country, and rates change on government schedules that a business has no visibility into unless it’s actively tracking them. A missed registration can mean months of retroactive liability by the time it’s caught.

• Audit exposure: Tax authorities can and do request transaction-level documentation going back several years during an audit. A business relying on static rates has no way to reconstruct what the correct rate should have been at the time of each sale.

Is your tax determination process built to scale?

To evaluate your tax determination process, look at what happens the next time your business adds a state, a country, or a product line. Pay attention to whether tax determination updates automatically or whether someone must notice the change and manually adjust a rate table. Learn whether the system distinguishes between a taxable SaaS subscription in New York and an exempt one in California, or if it applies a single rate everywhere.

You want a tax engine built to handle exactly this kind of variability. Here’s what to look for:

• Continuous rate coverage: It needs to calculate the applicable sales tax, VAT, or GST for each transaction using a database that covers each US state and country you sell in, updated as jurisdictions change their rules.

• Automatic product classification: It must apply product tax codes automatically, so a software subscription and a physical product don’t get treated the same way by default.

• Nexus tracking: It needs to track where your business is nearing or has crossed a nexus threshold based on actual transaction volume; this provides visibility into new registration obligations before they become back tax liability.

• Checkout integration: The calculation needs to happen at the point of sale (POS) rather than as a separate step your business has to reconcile afterward.

Though these features won’t eliminate your business’s registration obligations in the jurisdictions where it owes tax, they can greatly reduce your manual work.

How Stripe Tax can help

Stripe Tax reduces the complexity of tax compliance so you can focus on growing your business. Stripe Tax helps you monitor your obligations and alerts you when you exceed a sales tax registration threshold based on your Stripe transactions. In addition it automatically calculates and collects sales tax, VAT, and GST on both physical and digital goods and services—in all US states and in more than 100 countries.

Start collecting taxes globally by adding a single line of code to your existing integration, clicking a button in the Dashboard, or using our powerful application programming interface (API).

Stripe Tax can help you:

• Understand where to register and collect taxes: See where you need to collect taxes based on your Stripe transactions. After you register, switch on tax collection in a new state or country in seconds. You can start collecting taxes by adding one line of code to your existing Stripe integration or add tax collection with the click of a button in the Stripe Dashboard.

• Register to pay tax: Let Stripe manage your global tax registrations and benefit from a simplified process that prefills application details—saving you time and simplifying compliance with local regulations.

• Automatically collect tax: Stripe Tax calculates and collects the right amount of tax owed, no matter what or where you sell. It supports hundreds of products and services and is up-to-date on tax rules and rate changes.

• Simplify filing: Stripe Tax seamlessly integrates with filing partners, so your global filings are accurate and timely. Let our partners manage your filings so you can focus on growing your business.

Learn more about Stripe Tax, or get started today.