Buy a $1,000 laptop in Oregon and you pay $1,000. Buy it in Chicago and you pay $1,102.50. Sales tax is not one tax — it is a stack of state, county, and city taxes that varies by the block, by the product, and even by whether you bought it online. Here is how the system actually works.
Sales tax is a stack, not a single rate
Almost everywhere you shop, the rate on your receipt is the sum of several layers:
- State base rate — set by the state legislature, ranging from 0% (five states have no statewide sales tax) to over 7%.
- County add-on — counties can levy their own tax on top, often 0.5–2%.
- City and special-district add-ons — cities, transit districts, and stadium authorities can each add a slice.
The combined rate is what you actually pay. That is why the rate can change across the street: a store on the city side of a boundary charges the city layer, while the store across the road does not. Combined rates above 10% are common in parts of Louisiana, Tennessee, Arizona, and California; combined rates under 5% are common in much of the interior West.
What gets taxed — and what does not
Sales tax applies to tangible personal property by default: the shirt, the phone, the furniture. The exceptions are where it gets interesting, and they differ by state:
- Groceries: most states exempt unprepared food or tax it at a reduced rate. A few states — including Alabama, Mississippi, and South Dakota — tax groceries at the full rate.
- Clothing: a handful of states exempt it (Minnesota, New Jersey, Pennsylvania, and others with various limits); Massachusetts exempts clothing under $175.
- Prescription drugs: exempt in nearly every state.
- Services: traditionally untaxed, but a growing number of states tax things like software, streaming, car repairs, and landscaping. This is the fastest-changing part of the tax code.
- Digital goods: about half the states tax downloads, e-books, and streaming subscriptions; the other half treat them as untaxable intangibles.
Sales-tax holidays — the back-to-school weekends in August — temporarily exempt specific categories like clothing under $100 or school supplies. They are popular, but economists note retailers often just shift promotions around them.
Online purchases: the Wayfair rule
Before 2018, online sellers only had to collect sales tax in states where they had a physical presence. The Supreme Court's South Dakota v. Wayfair decision changed that: states can now require sellers to collect based on economic nexus — typically $100,000 in sales or 200 transactions into the state per year. Every state with a sales tax has since adopted such a law.
On top of that, marketplace facilitator laws require platforms like Amazon, eBay, Etsy, and Walmart to collect tax on third-party sellers' transactions. The practical result: when you buy online today, the tax is collected at checkout based on your delivery address in the vast majority of cases. The era of tax-free internet shopping is effectively over.
Worked example: the true cost of a $2,000 sofa
Three shoppers buy the same $2,000 sofa online, delivered to their homes:
- Portland, Oregon: 0% statewide tax → $2,000.00.
- Austin, Texas: 6.25% state + 1% city + 1% transit = 8.25% → $2,000 × 1.0825 = $2,165.00.
- Chicago, Illinois: 6.25% state + county and city layers totaling 10.25% → $2,000 × 1.1025 = $2,205.00.
The identical purchase costs $205 more in Chicago than in Portland — over 10% — purely from tax. On big-ticket items (appliances, furniture, vehicles), looking up the combined rate before you commit is worth real money. Many states publish ZIP-code rate lookup tools, and most large retailers show the tax line before you pay.
Big purchases: cars and the trade-in trick
Vehicles deserve special attention because the tax base is huge. Most states charge sales tax on vehicle purchases — and on trade-ins, the rules vary: many states tax only the difference between the new car price and the trade-in value, which can save hundreds. A few states tax the full price regardless. Leases are taxed too, usually on the monthly payments. If you are buying across state lines, you generally pay the tax rate of the state where you register the vehicle, not where you bought it — dealers near borders deal with this constantly.
How to estimate the true cost quickly
For everyday shopping, the mental shortcut is to round the combined rate to the nearest whole percent and multiply: a $75 item in an 8.25% area costs roughly $75 + $6 = $81. For precision — on purchases over a few hundred dollars, or when comparing prices across stores in different tax jurisdictions — use a calculator with the actual combined rate for your ZIP code. A 2% rate difference on a $3,000 appliance is $60, which is worth sixty seconds of checking.
Frequently asked questions
Which state has the highest sales tax?
Tennessee and Louisiana are usually at the top for combined state-plus-average-local rates, both above 9.5%. At the other end, Alaska, Delaware, Montana, New Hampshire, and Oregon have no statewide sales tax — though Alaska allows local sales taxes. Your actual rate depends on the city and county, not just the state.
Do I pay sales tax on online purchases?
In most cases, yes. Since the Supreme Court's 2018 Wayfair decision, states can require out-of-state sellers with enough sales in the state to collect sales tax. Major online retailers now collect at checkout in nearly every state with a sales tax, and marketplace laws make platforms like Amazon and eBay collect on behalf of third-party sellers.
Is sales tax charged on groceries?
It depends on the state. Most states exempt or reduce tax on unprepared groceries, but a handful — including Alabama, Mississippi, and South Dakota — fully tax grocery food at the regular rate. Prepared restaurant food is taxed almost everywhere, usually at the full rate.
What is the difference between sales tax and use tax?
Sales tax is collected by the seller at the point of sale; use tax is what you owe the state when you buy something taxable without paying sales tax — for example, from an out-of-state seller that did not collect. In practice, consumer use tax is rarely enforced, but businesses are audited on it regularly.