Managing Sales Tax Across Multiple States: A Practical Playbook

Most owners who sell across state lines already suspect they owe sales tax somewhere they are not collecting it. The harder questions decide the dollar amount: which states, starting when, on which products, and how much has built up since the day you crossed the line.

This playbook works those questions in the order we do in practice: find nexus, size the exposure, clean up the past, register in the right sequence, then set up collection and filing so the problem stays solved. The only prerequisite is accurate sales data by ship-to state.

Step one: find out where you have nexus

Since South Dakota v. Wayfair (June 21, 2018), a state can require you to collect its sales tax based on sales volume alone. The South Dakota law the Court upheld used $100,000 in sales or 200 transactions, and most states copied it. The trend since has run one way: as of August 2026, seventeen states have dropped the transaction count, including Illinois (January 1, 2026) and Kentucky (August 1, 2026). The big outliers are California and Texas at $500,000, New York at $500,000 and more than 100 sales, and Alabama at $250,000.

Economic nexus is only half the test. Physical presence still creates nexus everywhere, and it is easier to trigger than most owners think: a remote employee working from home in Georgia, a contractor installing your product in Ohio, a trade show booth, or inventory in a third-party warehouse. Florida treats inventory in an in-state fulfillment center as physical presence regardless of sales volume, and most states agree; Pennsylvania's Commonwealth Court is the notable exception, ruling in 2022 that merchandise in an Amazon warehouse, by itself, did not create nexus for an out-of-state seller.

Here are the thresholds for states a Florida seller most often ships into, checked against state guidance in September 2026. States change these rules often, so confirm before relying on any row.

Notice the measurement periods. Texas and Illinois use a rolling twelve months, Florida looks only at last calendar year, and Georgia and Ohio count this year and last, so a seller can be over the line in Texas today and not in Florida until January. The review has to run per state. If the concept is new, start with our plain-English explanation of nexus.

Step two: size the exposure before you register

Registering tells the state you exist. If you crossed a threshold two years ago, registering today without a plan invites the question "and what about the last two years?" So before any registration, estimate the back liability: taxable sales into the state after nexus began, times the average combined rate, plus interest. Where you never filed, the exposure can reach back to the day nexus started, because the limitations period never starts on an unfiled return.

If the number is meaningful, a voluntary disclosure agreement (VDA) is usually the right tool. In a typical VDA the state limits the lookback to three or four years, waives penalties, and still charges interest in full. The catch is that you must come forward before the state contacts you and, in most states, before you register. Your accountant can approach the state anonymously, and the Multistate Tax Commission runs a program covering several states at once. Timing matters this fall: Illinois is running a remote retailer amnesty from August 1 through October 31, 2026 that waives penalties and interest on eligible 2021 through mid-2026 sales, paid at a simplified flat rate.

Step three: register in the right order

Home state first, always. Next come states where you have physical presence, because those obligations have no threshold and usually the longest exposure. Then the economic nexus states, ranked by dollars at risk. Do not register where you have no nexus "to be safe": every registration creates a filing obligation, including zero returns, and a state that has you on file will notice the missing ones.

The Streamlined Sales Tax (SST) system saves real time in its 24 member states (23 full members plus Tennessee as an associate), including Georgia, North Carolina, Ohio, Indiana, Michigan and Washington. Registration through the SSTRS portal is free, you select only the member states where you have nexus, and qualifying volunteer sellers can use a certified service provider at no charge. SST does nothing for Florida, Texas, California, New York or Pennsylvania, so most sellers end up with a mix of SST and direct registrations.

Two simplifications are worth knowing: Texas lets remote sellers collect a single local use tax rate of 1.75% on top of the 6.25% state rate, and Alabama's Simplified Sellers Use Tax program lets remote sellers collect a flat 8% statewide.

Step four: set up collection, filing frequency and the calendar

Each state assigns a filing frequency based on volume, and it is rarely the same across states. Florida puts you on monthly returns if you collect more than $1,000 a year, quarterly at $501 to $1,000, semiannual at $101 to $500, and annual at $100 or less, with returns due on the first and late after the 20th of the following month. Other states use the 20th, the 25th, or the last day. Put every due date on one calendar and file the zero returns; a missed zero return generates the same notice as a missed real one.

Taxability is where multi-state sellers make the most expensive mistakes, because the same product is not taxable in every state. Most states tax tangible goods and exempt services unless a service is specifically listed. Texas taxes data processing on 80% of the charge, Washington added IT services, advertising and temporary staffing to its sales tax on October 1, 2025, and online software is taxable in Texas, New York, Pennsylvania and Washington but not in Florida; California starts taxing it January 1, 2027. Shipping is its own puzzle: Florida exempts a separately stated, optional delivery charge, while many states tax delivery whenever the goods are taxable. Our guide to sales tax on services covers this ground.

Marketplace sales add a wrinkle. Every state with a sales tax now makes Amazon, Walmart, Etsy and eBay collect on the orders they facilitate (Missouri was last, on January 1, 2023), but whether those sales count toward your threshold depends on the state: Texas and North Carolina count them, while Florida, Alabama and Pennsylvania exclude them when the marketplace collects. A seller with $90,000 of direct and $60,000 of Amazon sales has crossed in North Carolina but not in Pennsylvania. See our marketplace facilitator guide.

Worked example: a Tampa e-commerce seller crosses three thresholds

Suppose a Tampa company sells specialty kitchen equipment from its own website, with $2.4 million in annual sales shipped nationwide and no marketplace channel. It is registered in Florida. During 2026 three more states come into play.

Georgia. By late September, Georgia shipments reach $104,000 across 1,650 orders. Georgia uses either $100,000 or 200 sales in the current or previous calendar year, so this seller crossed the transaction test back in the spring, at order 200, and every Georgia sale since then should have carried tax. Say that is $70,000 of taxable sales at an assumed blended 7.5% rate (4% state plus local taxes): roughly $5,250 the company must now fund from margin, plus interest, and penalties if Georgia finds it first.

Texas. Rolling twelve-month Texas revenue passes $500,000 in March 2026. Texas gives a clear runway: the permit and collection must be in place by the first day of the fourth month after the month the threshold was exceeded, so July 1, 2026. The company registers in June, elects the 1.75% single local rate, and collects 8% on Texas orders from July 1, with no back liability.

North Carolina. Sales cross $100,000 in August 2026. Under the rule adopted July 2, 2026, a threshold-only seller becomes engaged in business on the first day of the first calendar month at least 60 days after crossing, which lands on November 1. Registration in October, collection from November 1, nothing owed for earlier months.

Three states, three measurement periods, three start dates. The Georgia problem exists only because nobody was watching the order count; a quarterly report of dollars and orders by ship-to state would have caught it in April.

Automation tools and what they cannot do

Rate calculation at checkout is a solved problem. Shopify Tax, Avalara, TaxJar and similar tools apply the right combined rate to the right address, and most can file the returns. What they cannot do is decide where you have nexus (they see only the channels connected to them, never the employee you hired in Denver), classify your products, or fix the past. The most common automation failure we see is a tool collecting in a state where the company never registered, so tax sits in the bank with nowhere to go.

What usually goes wrong

The same handful of problems shows up in almost every multi-state cleanup. Sellers measure nexus by billing address instead of ship-to address. They watch dollars and forget the transaction count in states that still have one. They register in a state and never file because sales were small, then meet the notices for the skipped zero returns. They use a home-state resale certificate in a state that does not accept it. And they book collected sales tax as income, which overstates revenue and hides the liability; our monthly bookkeeping checklist includes the reconciliation that catches it.

When to get help

If you sell into more than a few states and have never run a nexus study, or suspect you crossed a threshold in a prior year, do the study before anything else. The order of operations (measure, disclose, register, then automate) keeps a fixable problem from becoming a multi-state audit. Our sales tax compliance service handles the nexus review, VDA negotiations, registrations and the filing calendar as one engagement, so nothing falls between your bookkeeper and your software.

For a second set of eyes on your ship-to data, request a 20-minute fit call. Bring a sales-by-state report for the last two years and we will tell you where you stand.

Jenny Gao, CPA, EA

Founder of Balance Partners. Florida-licensed CPA and IRS Enrolled Agent with more than a decade of accounting and tax experience. Jenny writes and reviews every guide on this site. About Jenny

This article is general educational information for U.S. business owners and is not accounting, tax, legal, payroll or financial advice for your situation. Rules change and vary by entity, state and facts. Balance Partners, LLC does not provide audit, review or other attest services. Last reviewed September 14, 2026.