How sales tax filing works for small businesses

Sales tax tends to come up every month or quarter with the same questions: how much is owed, and when is it due? Understanding the calendar lowers the risk of a missed deadline and makes cash planning easier.

This guide covers the general framework. Rates, thresholds and due dates are set by each state and can change.

Who sets sales tax rules?

There is no federal sales tax. Each state that has a sales tax decides what goods and services are taxable, which rates apply and how returns are filed. Counties, cities and special districts can add their own rates on top.

That means a business selling in several states may follow several sets of rules. In North Carolina, for example, registration, returns and payments go through the NC Department of Revenue.

How is the amount figured?

On each taxable sale, the business adds sales tax at the rate that applies to that sale and collects it from the customer. That money belongs to the state, so it should be kept separate from operating cash.

At the end of each period, the return reports gross sales, exempt sales and taxable sales, and the tax collected is remitted. Our sales tax calculator shows the math for a single sale using a rate you enter.

How often do you file?

When you register, the state assigns a filing frequency, typically monthly, quarterly or annual. Businesses with more sales are usually placed on a more frequent schedule, and the state can change your frequency as your sales change.

A return is generally due for every period while your account is open, including periods with no sales. We build each client's filing calendar at onboarding and track every due date. The process is described on our sales tax page.

What does economic nexus mean for remote sellers?

Before 2018, a state could generally require collection only from sellers with a physical presence there. In South Dakota v. Wayfair, the Supreme Court allowed states to require collection based on sales into the state.

Each state now sets its own economic nexus threshold, measured by sales revenue, number of transactions or both. If you sell online or ship across state lines, it is worth reviewing your sales by state at least once a year.

What happens if you file or pay late?

Late returns and late payments can bring penalties and interest under state law. The amounts and rules differ by state, so check your state's current guidance.

Most late filings start with missing information. Getting sales reports and exemption certificates to your bookkeeper before the period closes keeps the return on time. Keep the supporting records as long as your state requires, and see how long to keep tax records for the federal side.