A compliance notice from a state we'd never had an office in showed up in our inbox eighteen months after we crossed its revenue threshold. By then we owed back tax, penalties, and interest, plus a finance conversation I could have avoided with twenty minutes of research the week we signed our first customer there.
Founders treat sales tax like a brick-and-mortar problem. It isn't anymore, and for SaaS specifically, the rules are messier than almost any other product category.
Why SaaS founders get caught off guard
Nearly every state with a sales tax now enforces economic nexus: once your revenue into that state crosses a threshold, commonly $100,000 in trailing-12-month sales, you owe tax there whether or not you have an office, a warehouse, or a single employee in it. No physical presence required. Just revenue.
2026 made this tighter, not looser. Illinois removed its 200-transaction alternate threshold this year, which matters most if you sell a low-volume, high-ticket product, a handful of large enterprise contracts can now trip nexus that a pile of small transactions never would have. Several other states expanded what counts as a taxable digital service, pulling more SaaS products into scope than in 2024 or 2025.
Then there's the part that trips up almost every SaaS founder specifically: whether SaaS is taxable at all varies state by state, and doesn't track any pattern you'd guess from the outside. Washington and New York tax SaaS broadly. Several other states tax it only for consumer use and exempt business use, or the reverse. A handful barely tax it at all under current guidance. You cannot apply one state's answer to another state's question, and you cannot assume the rule you read in 2024 is still the rule in 2026.
One more trigger founders miss entirely: a single remote employee working from their home in another state can create physical nexus in that state, immediately, regardless of your revenue there. If your five-person team is distributed across four states, you may already have nexus obligations you've never checked, independent of how much you sell.
The mistake: waiting for software to catch it
Most founders' actual plan is "we'll deal with it when we're bigger" or "the nexus tracking tool will flag it." Both are backwards. Nexus tools are useful, but they tell you after you've crossed a threshold, which means you've already been selling taxable product in that state for however long it took you to notice the alert. Registration after the fact doesn't erase the exposure, it just starts the clock on back taxes, penalties, and interest for the period you were already over the line, sometimes with no statute of limitations protection if you never registered at all.
The founders who avoid the notice are the ones who check this quarterly, not the ones with the best software. This is a spreadsheet problem before it's a software problem.
The checklist: what to actually check this week
- Pull trailing-12-month revenue by customer billing state.
Most billing systems (Stripe included) can export this in a few minutes. This is the number everything else depends on, and almost no founder has looked at it broken out this way before.
- Check every state where you're above roughly $50,000 against its current threshold and current SaaS taxability rule.
$50,000 isn't a legal cutoff, it's a working buffer, so you catch a state before it crosses the more common $100,000 threshold, not after. Don't extrapolate one state's SaaS rule to the next; check each one specifically.
- List every state where you have a remote employee or contractor, regardless of revenue.
That's physical nexus, and it doesn't care how small your sales in that state are.
- Register in any state you've already crossed, before you sell there again, not after your next renewal.
Every additional month unregistered is another month of exposure with no protection.
- Decide now whether your price is tax-inclusive or tax-added, before more customers are used to the number they see today.
Changing this after a large base already expects one number is its own retention problem, separate from the tax problem itself.
What ignoring it actually costs
Say you did $180,000 in trailing revenue in a state with a 6% rate and a $100,000 threshold, and you didn't notice for a year after crossing it. That's roughly $4,800 in tax on the amount above threshold, before penalties, which many states apply as a percentage per month unregistered, and before interest, which compounds the whole time. On a single state, that's a few thousand dollars and an unpleasant afternoon. Multiply it by the four or five states most 0-to-1 SaaS companies quietly cross within two years of their first out-of-state enterprise deal, and it stops being a rounding error and starts being a real hit to a cap table that was already tight.
The checklist above costs an afternoon. The notice costs a lot more than that, and it always arrives at the worst possible time, usually right before a fundraise or an acquisition due diligence process, when a new liability on the books is the last thing you want to be explaining.
Frequently asked questions
Does my SaaS company need to charge sales tax?
It depends on the state and whether that state taxes SaaS at all, plus whether you've crossed its economic nexus threshold there. There's no single national answer; it has to be checked state by state.
What is economic nexus?
A rule that requires you to collect and remit sales tax in a state once your sales there cross a revenue threshold, commonly $100,000, even with zero physical presence in that state.
Which states tax SaaS?
It varies and changes yearly. States like Washington and New York tax SaaS broadly. Others tax only consumer use or only business use, and some barely tax it under current guidance. Check each state you have real revenue in individually rather than assuming one rule applies everywhere.
What happens if I ignore nexus obligations?
You accrue back tax for the period you were over the threshold, plus penalties and interest, and in states where you never registered, there may be no statute of limitations protecting you from that exposure.
Do remote employees create nexus even without meeting the revenue threshold?
Yes. A single remote employee or contractor working from a state can create physical nexus there immediately, independent of how much revenue you generate in that state.
This isn't a one-time check. Revisit the state-by-state list every quarter as revenue shifts, because the threshold you're nowhere near in January is often the one you've quietly crossed by September. If you want help figuring out where your actual exposure sits before you register anywhere, that's the kind of thing we help founders work through.