How do state sales and use taxes differ and why does it matter?

State sales and use tax systems are a patchwork: each state sets a base sales tax rate, decides which goods and services are taxable, and then allows local governments to add their own levies. The practical result is that the same purchase—say, a laptop or a contractor service—can be taxed differently depending on where you buy it, where you receive it, and whether the seller collected tax at the point of sale.

This matters because sales tax is typically collected by the seller and remitted to the state, while use tax is the responsibility of the buyer when sales tax was not collected (for example, purchases from out-of-state sellers or some online sales). Failing to account for use tax creates an exposure that can lead to assessments, penalties, and interest on audit.

Sources and legal context

  • South Dakota v. Wayfair, Inc. (2018) removed the physical-presence requirement for state sales tax collection and allowed states to require remote sellers to collect sales tax when they meet economic thresholds. This has been the primary driver of increased enforcement against online sellers.
  • The IRS maintains a general overview of state sales and use tax issues for businesses (IRS, Sales and Use Tax Information) and the Consumer Financial Protection Bureau and Treasury provide context on state taxation trends and consumer impacts.

Authoritative resources:

In my practice I’ve seen small businesses and nonprofits misunderstand when use tax applies after a cross-border purchase. Properly documenting purchases and using either automated tools or a clear reporting process usually stops small exposures from becoming large problems.

Key differences explained

  1. Tax base: what is taxable
  • States differ in which goods and services are taxable. Many states tax tangible personal property but vary widely on services (e.g., digital subscriptions, repairs, professional services). Essentials such as groceries, prescriptions, or clothing may be exempt in some states and taxable in others.
  • Example: Digital goods are taxable in many states now; sellers should verify whether their products are classified as taxable tangible goods or taxable services under a given state’s law.
  1. Rates and local add-ons
  • Each state sets a base rate; counties and cities may add surtaxes. That causes wide variation in total rates. For example, California’s statewide base rate is 7.25% (local add-ons can push totals above 10% in some cities), Texas’s base is 6.25% (local additions can bring totals to about 8.25%), and New York’s base is 4% (combined local rates create higher totals in many municipalities such as New York City at 8.875%). Check state tax agencies for current local totals.
  • Because rates change and local ballot measures occasionally increase local sales taxes, rely on state revenue departments for the latest rates rather than static lists.
  1. Nexus and who must collect
  • Nexus is the connection that allows a state to require a seller to collect sales tax. After Wayfair, economic nexus thresholds (e.g., $100,000 in sales or 200 transactions in a state) allow states to require collection even without a physical presence.
  • Nexus rules differ by state and by type of business activity (goods, services, digital goods). Businesses selling across state lines must evaluate nexus for each state where they reach the threshold.
  1. Sourcing rules: where is the sale taxed?
  • Origin-based states tax at the seller’s location; destination-based states tax where the buyer receives the goods or service. Many states use destination sourcing for retail sales and origin for certain service transactions or business-to-business transfers.
  • For remote sellers, this affects which rate to charge for a particular order and makes proper address capture and tax-automation critical.
  1. Use tax enforcement and reporting
  • Use tax is often reported on the buyer’s state income or sales tax return, or through a separate use tax return. States increasingly match purchase data from large marketplaces and card processors to discover uncollected tax.
  • Audits and voluntary disclosure programs: If a business or individual discovers unreported use tax, many states offer voluntary disclosure agreements (VDAs) that limit prior-period liability if you come forward voluntarily. This is a practical remedy in my experience for cleaning up older exposures without full-blown audit penalties.

Practical implications for consumers and businesses

Consumers

  • Large out-of-state purchases: If a retailer doesn’t collect sales tax, expect to report and pay use tax on your state return. Some states provide a simplified household use tax summary or allow you to report small amounts directly on your income tax return.
  • Keep receipts and track online marketplace purchases. Marketplaces may collect tax on behalf of multiple sellers, but you still need evidence of tax paid if you are audited.

Businesses

  • Registration: Register for sales tax permits in any state where you have nexus. Filing without registration risks penalties. For guidance, see resources like our Sales Tax Compliance guidance for online sellers.
  • Exemptions and resale certificates: Maintain valid exemption documentation for purchases claimed exempt (resale, manufacturing inputs, nonprofit exemptions) and accept properly completed resale certificates when selling to resellers.
  • Software and automation: Use tax engines that handle nexus tracking, rate tables, and sourcing. Automation reduces errors and provides an audit trail.

Internal links and further reading

Common mistakes and how to avoid them

  1. Assuming online purchases are always tax-free
  • After Wayfair, many online sellers must collect tax. If a seller doesn’t collect tax, don’t assume you’re exempt—track and report use tax if required.
  1. Poor documentation for exemptions
  • Keep properly completed resale or exemption certificates for every exempt sale or purchase. States will disallow undocumented exemptions in audits.
  1. Incorrect sourcing and rate application
  • Use address verification and a tax engine to apply the correct jurisdictional rate. Small rate differences multiply with frequent transactions.
  1. Ignoring marketplace collection rules
  • Many states hold marketplaces responsible for collecting sales tax on marketplace sales. Confirm whether sales through a marketplace are being collected and how that affects your reporting.

Practical checklist for compliance

  • Determine where you have nexus (economic and physical).
  • Register for sales tax permits in each state where you have nexus.
  • Configure sourcing rules in your billing/purchase flow and use a tax engine or updated rate tables.
  • Keep receipts, exemption certificates, and shipping records for at least the period required by state law (commonly 3–7 years).
  • Reconcile marketplace-collected sales to your books and keep evidence of tax collection.
  • Consider a voluntary disclosure if you have a past-use tax exposure.

Professional tips

  • In my practice I recommend an annual sales-tax compliance review for any business selling out of state—this often uncovers overlooked nexus created by trade shows, remote employees, or affiliate relationships.
  • If you operate in many states, centralize your documentation and routing of sales tax questions: a single process for exemption certificates and a cloud repository for receipts helps during audits.

FAQs (brief)

Q: Who pays use tax?
A: The buyer generally owes use tax when sales tax was not collected at purchase; businesses often report use tax on sales tax returns.

Q: Can states audit for use tax?
A: Yes. States increasingly use third-party data and marketplace reporting to identify uncollected tax and may audit both businesses and individuals.

Q: What is a safe first step if I find unreported use tax?
A: Contact a state’s voluntary disclosure program or a tax professional. Many states provide relief from penalties if you voluntarily disclose and pay past liability.

Professional disclaimer

This article is an educational overview and not personalized tax advice. State sales and use tax rules change frequently; consult a qualified tax professional or the relevant state department of revenue for advice tailored to your situation.

Sources and further reading