🛒 Online Sales Tax Calculator 2026

Online Sales Tax: The Post-Wayfair Landscape

The 2018 Supreme Court decision in South Dakota v. Wayfair fundamentally changed online sales tax. Before Wayfair, online sellers only had to collect sales tax in states where they had a physical presence (nexus). After Wayfair, states can require out-of-state sellers to collect and remit sales tax based on economic nexus — typically triggered by exceeding $100,000 in sales or 200 transactions in that state within a calendar year. As of 2026, every state that has a sales tax has enacted economic nexus laws. This means an eCommerce seller based in California must collect and remit Washington state sales tax if they sell more than $100,000 to Washington customers, even without a single employee or building in the state.

Economic Nexus Thresholds by State

The most common economic nexus threshold is $100,000 in sales or 200 transactions in a 12-month period — adopted by the majority of states following South Dakota’s model. Notable variations: California maintains the $500,000 revenue threshold for marketplace facilitators. Some states have eliminated the transaction count threshold and use revenue only. Texas, Florida, and several other large states use $100,000 in taxable sales only. For sellers growing into new markets, monitoring sales volume by state is essential — crossing an economic nexus threshold creates an obligation to register, collect, and remit in that state within a short window (often 30–60 days). Missing this deadline results in back taxes, interest, and potential penalties.

Destination vs Origin-Based Sales Tax

Most states are destination-based: sales tax is based on the buyer’s location (where the item is delivered), not the seller’s location. This is why an online seller in one state must charge the buyer’s state’s tax rate. A handful of states — including Arizona, California, Illinois, Missouri, Ohio, Pennsylvania, Tennessee, Texas, Utah, and Virginia — are origin-based for intrastate transactions (seller and buyer in same state), meaning the rate is based on where the seller is located within the state. For interstate transactions, federal law effectively requires destination-based taxation. This distinction matters most for sellers who have nexus in multiple locations within the same state.

Marketplace Facilitator Laws: Amazon, Etsy, eBay, and Shopify

All 50 states (plus DC) with sales taxes now have Marketplace Facilitator (MPF) laws requiring platforms like Amazon, Etsy, eBay, Walmart Marketplace, and Poshmark to collect and remit sales tax on behalf of third-party sellers. This means individual sellers on these platforms are generally NOT responsible for sales tax collection on marketplace sales — the platform handles it automatically. However, sellers who also sell through their own website (Shopify store, WooCommerce) remain responsible for collecting and remitting tax on those direct sales if they have economic or physical nexus in the buyer’s state. Sellers operating on both marketplace and direct channels must track nexus separately for each channel.

Sales Tax Holidays and Product Exemptions

Many states offer annual sales tax holidays — typically one to three days — when certain items are exempt from sales tax. Common holiday categories: back-to-school supplies and clothing (Florida, Texas, Virginia, Ohio, and others), hurricane preparedness supplies (Florida), Energy Star appliances (several states). Product exemptions vary dramatically by state: groceries are exempt from sales tax in most states (but not in Alabama, Mississippi, and South Dakota as of recent years); prescription drugs are exempt in all states; clothing is taxed in most states but exempt in Pennsylvania, Minnesota, and New Jersey; digital products (ebooks, streaming, software) have varying treatment — about 30 states now tax digital downloads, while others do not. Understanding which of your products may be exempt in specific states is essential for accurate tax collection.