How do I set up sales tax/VAT/GST correctly for my online store?

Indirect taxes are among the most misunderstood obligations in e-commerce. Get them wrong and you face audits, penalties, and retroactive bills — get them right and you build a business that scales across borders without fear.

When you launched your online store, you probably focused on products, design, and marketing. Taxes — particularly the labyrinthine world of sales tax, VAT, and GST — likely felt like a problem for later. But “later” has a way of arriving all at once, usually in the form of a government notice or a costly audit. Understanding and correctly implementing consumption taxes is not just a legal obligation; it’s a foundation of financial integrity for any online business.

This guide walks you through everything you need to know: what each tax system is, when it applies to you, how to set it up on your store, and how to stay compliant as you grow.

Understanding the Three Major Systems

Before configuring a single setting, it helps to understand what kind of tax regime you’re dealing with. The world broadly operates under three systems, and your obligations depend entirely on where you sell and where your customers are located.

Tax Type	Where It Applies	Charged On	Key Feature
Sales Tax	United States, some Canadian provinces	End consumer only	Varies by state, county, and city
VAT	EU, UK, most of Europe, Middle East	Each stage of the supply chain	Businesses recover input tax; consumers bear final cost
GST	Canada, Australia, New Zealand, India, Singapore	End consumer (with business credits)	Functionally similar to VAT; often combined with other taxes

Key PrincipleThese are all forms of “consumption tax” — ultimately paid by the buyer, but collected and remitted by the seller. Your job is to collect the right amount from the right customers and send it to the right authority at the right time.

Step 1 — Determine Where You Have Tax Obligations

Not every transaction triggers a tax obligation. You must first understand the concept of nexus (in US sales tax terminology) or registration thresholds (in VAT/GST systems). This determines where you are legally required to collect and remit tax.

U.S. Sales Tax: The Nexus Question

Since the landmark 2018 South Dakota v. Wayfair Supreme Court decision, “economic nexus” means that even without a physical presence in a state, you may owe sales tax there once you exceed that state’s revenue or transaction threshold — typically $100,000 in sales or 200 transactions per year.

Physical nexus — offices, warehouses, employees, inventory in a fulfillment center — still applies everywhere. If you store products in an Amazon FBA warehouse in Ohio, you likely have nexus in Ohio.

Identify every state where you have employees, offices, or warehouses
Identify every state where you store inventory (including third-party fulfillment)
Review your sales volume in each state against their economic nexus thresholds
Register for a sales tax permit in every state where nexus exists — selling without a permit is a violation

EU VAT: Distance Selling & the OSS Scheme

If you sell physical goods or digital products to EU consumers, you must collect VAT. The EU’s One-Stop Shop (OSS) scheme — introduced in July 2021 — dramatically simplified things: register once in any EU country and you can collect and remit VAT for all 27 member states through a single return. The threshold before OSS registration is required is €10,000 in annual cross-border EU sales.

For non-EU sellers, you’ll typically register under the Import One-Stop Shop (IOSS) scheme if shipping goods valued under €150 to EU customers, or in individual EU countries if shipping higher-value goods.

UK VAT Post-Brexit

The UK now operates its own separate VAT system. The standard registration threshold for UK-based businesses is £90,000 in taxable turnover in a 12-month period. Non-UK businesses selling goods to UK consumers must register and charge UK VAT regardless of turnover.

Australia, Canada & Other GST Regions

Australia’s GST applies at 10% and foreign businesses must register once they expect to earn AU$75,000 in Australian turnover. Canada’s GST/HST regime has a simplified registration path for non-resident digital service providers. Always check the specific threshold for any market you’re targeting.

The single most expensive tax mistake e-commerce merchants make is not failing to collect tax — it’s collecting the wrong amount, or collecting without ever registering.

Step 2 — Register for the Right Tax Authorities

Registration comes before collection. You cannot legally charge sales tax in a U.S. state without first obtaining a sales tax permit from that state’s revenue department. Similarly, you must register for a VAT number before charging VAT in any jurisdiction.

U.S. States — Register through each state’s Department of Revenue website. Some states are free; others charge a small fee. This process is straightforward but repetitive if you have nexus in many states. Tools like TaxJar and Avalara can help manage multi-state registration.
EU OSS — Register through the tax authority of any EU member state of your choice. Most sellers choose a country with a good digital infrastructure (Germany, Ireland, or Netherlands are common). Complete the registration at that country’s tax portal.
UK — Register through HMRC’s online portal. Non-UK businesses use the same system; you’ll receive a UK VAT registration number starting with “GB.”
Australia — Register through the Australian Business Register (ABR) and apply for an ABN (Australian Business Number) along with GST registration.
Canada — Register for a GST/HST account through the CRA (Canada Revenue Agency) online portal. If you sell into Quebec, you’ll also need to register for Quebec Sales Tax (QST) separately.

⚠ Important: Never begin charging customers a tax before you have a valid registration number. Collecting tax without registration creates both a legal liability and a practical headache — you’d be holding tax you cannot legally remit.

Step 3 — Configure Your E-Commerce Platform

Once you know where you’re obligated and have your registration numbers, it’s time to configure your store. Most major platforms have built-in tax settings, though their sophistication varies considerably.

Shopify

Go to Settings → Taxes and Duties. Shopify auto-detects US nexus by state and calculates rates automatically. For EU/UK VAT, you enter your VAT number and configure rate rules by country. Shopify Tax (their premium service) provides more advanced US compliance.

WooCommerce

Enable taxes in WooCommerce Settings → General. Set up tax classes and rates under WooCommerce → Settings → Tax. For automated rates, use plugins like TaxJar, Avalara, or the native WooCommerce EU VAT plugin.

BigCommerce

Navigate to Store Setup → Tax. BigCommerce partners with Avalara for automated tax calculation. Enter your nexus states and VAT registration numbers, and the platform handles rate calculation at checkout.

Squarespace

Found under Commerce → Payments → Taxes. Squarespace supports automatic tax calculation for the US and several other countries. For complex multi-jurisdiction needs, manual rate setup or an external service may be required.

Critical Settings to Configure

Tax display: Should prices show tax-inclusive (common in EU/UK) or tax-exclusive (common in US)? This must match local consumer expectations and legal requirements
Tax on shipping: Some states and countries tax shipping charges; others don’t. Configure this accurately
Tax-exempt customers: Set up customer groups for B2B buyers with valid VAT numbers (EU reverse charge) or US resale certificates
Product tax categories: Different products may have different rates (e.g., food, children’s clothing, and digital goods often have special rates)
Digital goods: Most jurisdictions now tax digital products — software, e-books, courses, streaming — and the rules differ significantly from physical goods

Step 4 — Handle Product Classification Carefully

Not all products are taxed at the same rate — and some aren’t taxed at all. Misclassifying a product can mean either overcharging your customers (creating a trust issue and refund liability) or undercharging (creating a tax liability you’ll owe out of pocket).

Common Rate Exceptions to Know

In the US, groceries, prescription drugs, and children’s clothing are exempt from sales tax in many states. In the EU and UK, food products often carry a reduced or zero VAT rate, while luxury goods may carry standard or higher rates. Australia’s GST exempts fresh food, medicines, and some education materials.

Digital products deserve special attention. The EU taxes digital services at the buyer’s country rate, not the seller’s. A UK customer buying a software subscription from a US company pays UK VAT at 20%. A French customer pays French VAT at 20%. This “destination-based” rule applies across most modern VAT/GST systems for digital services.

B2B Sales & the Reverse ChargeWhen selling to VAT-registered businesses in the EU, you typically don’t charge VAT — instead, the buyer “self-assesses” the tax under the reverse charge mechanism. Collect and verify your customers’ VAT registration numbers (the EU’s VIES system lets you validate them online) and issue invoices marked “VAT reverse charge applies.” This is a significant simplification for B2B cross-border sales.

Step 5 — Set Up Automated Tax Calculation

For small stores selling in one or two jurisdictions, manual rate management is feasible. But as you grow, the complexity compounds quickly — the US alone has over 11,000 different tax jurisdictions. Automation is not a luxury at that point; it’s a necessity.

The leading tax automation services integrate directly with all major e-commerce platforms and handle rate calculation in real time at checkout, rooftop-level accuracy (down to the specific street address), automatic updates when rates change, and filing reports that simplify returns.

TaxJar — Excellent for US sales tax; strong filing automation and nexus tracking
Avalara AvaTax — Comprehensive global coverage; better for larger merchants with international presence
Quaderno — Strong focus on digital goods and subscription businesses; excellent EU VAT handling
Stripe Tax — If you use Stripe as your payment processor, Stripe Tax is an elegant built-in option
Taxamo (Vertex) — Specialist in digital services VAT/GST globally

Step 6 — File Returns & Remit Taxes on Time

Collecting tax is only half the job. You must remit what you’ve collected to the relevant authority by specified deadlines — and file returns even in periods where you collected nothing (most jurisdictions require “zero returns”).

Filing Frequencies

In the US, filing frequency varies by state and by your sales volume in that state — typically monthly, quarterly, or annually. Higher-volume sellers file more frequently. The EU’s OSS requires a quarterly return. The UK requires quarterly VAT returns by default. Australia’s BAS (Business Activity Statement) including GST is filed monthly or quarterly.

Missing a filing deadline results in penalties and interest. Missing multiple deadlines can trigger audits. Build tax filing dates into your financial calendar the same way you track payroll or rent.

Export your sales tax data from your store platform or tax automation tool at the end of each reporting period.
Reconcile the collected amounts against what your platform processed. Discrepancies should be investigated before filing.
Complete the return — either manually through the tax authority’s online portal, or automated through your tax service.
Submit payment of the net tax due (VAT/GST: remember to claim input tax credits if applicable). Keep confirmation records for at least 7 years.

Common Mistakes to Avoid

Collecting without a permit: Always register before you collect. Retroactive registration is possible but painful
Ignoring economic nexus: Monitor your state-by-state US sales quarterly to catch threshold crossings promptly
Using the wrong address: Tax calculation depends on the delivery address, not your store’s address. Ensure your platform captures ship-to addresses accurately
Forgetting marketplace facilitator rules: If you sell on Amazon, Etsy, or eBay in the US, those platforms collect and remit sales tax on your behalf in most states — don’t double-collect
Neglecting record-keeping: Tax authorities can audit years of past transactions. Keep invoices, returns, and payment confirmations meticulously
Treating digital goods like physical goods: The tax rules are often completely different — check each jurisdiction’s specific rules for your product type

When to Hire Professional Help

A tax automation tool handles the mechanics, but it doesn’t replace professional judgment. You should consult a tax professional (ideally one specializing in e-commerce or international tax) when you first launch internationally, when you approach nexus thresholds in new jurisdictions, if you receive a notice or audit from any tax authority, when structuring your business entity (the legal structure affects your tax obligations), and when your revenue grows past the point where DIY compliance becomes genuinely risky.

The cost of an hour with a qualified tax advisor is invariably less than the cost of a penalty — and far less than the cost of back taxes owed across multiple jurisdictions.

The merchants who sleep soundly aren’t the ones who never think about taxes — they’re the ones who set up good systems early and maintain them consistently.

A Final Word on Staying Current

Tax law is not static. Rates change. New jurisdictions introduce registration requirements. Thresholds are adjusted. New categories of digital goods are brought into scope. The EU’s VAT system alone has undergone multiple major overhauls in the past decade, and further changes are always in progress.

Subscribe to updates from your tax automation service. Follow relevant tax authority bulletins. Review your nexus positions at least quarterly as your business grows. What was compliant last year may not be compliant today.

Setting up consumption taxes correctly is one of those unglamorous but genuinely important foundations of a sustainable online business. Do it properly once, maintain it diligently, and it becomes one less thing standing between you and the work you actually love doing.

This article is for general informational purposes only and does not constitute legal or tax advice. Consult a qualified tax professional for guidance specific to your business and jurisdiction.