Know the day you owe sales tax in a new state, before the state does.
Sales-Tax Nexus Monitor watches the sales feed you already have, groups it by the state your buyers are in, and tells you exactly where your revenue or your order count has crossed that state's economic-nexus threshold (and where you are getting close). Not a filing suite, not a confidence score, a plain answer per state with the crossing evidence attached.
Run the nexus monitor on your own sales See a sample nexus report
THE PROBLEM
Since South Dakota v. Wayfair, you owe sales tax in a state once your sales into that state pass a threshold (usually a dollar amount, sometimes a transaction count, and the two states next to each other rarely agree on the number). The trap is that it happens quietly. You cross the line in the middle of a growth month, you keep shipping and never collect the tax, and the uncollected amount plus penalties and interest just sits there compounding until a state notice lands, an auditor asks, or a buyer's diligence team finds it and shaves the number off your valuation. Most sellers find out late, from someone who is not on their side, and the popular fix (a second tool that guesses whether you might have nexus) is exactly the kind of soft answer that does not hold up when a real dollar figure is on the line.
HOW IT WORKS
The monitor does not touch your books and it does not file anything, it reads the sales feed you already produce. For each state, it adds up your in-scope revenue and counts your qualifying transactions over the measurement window, then compares both against that state's threshold, honoring how the state combines them (some states use revenue or transactions, some require both). Where the arithmetic can decide the case you get a decisive label, crossed, approaching, or clear, and when a state is crossed you get the receipt (which prong tripped, the value, the threshold, and by how much you went over). Where the monitor has no validated number for a state, it says so honestly (unknown jurisdiction) instead of painting a green light it cannot defend, and if your feed is malformed it fails closed rather than reporting a false all-clear. It is deterministic and model-free at evaluate time, so the same feed always gives the same answer.
WHAT YOU GET (the nexus report)
One rolling report across every state you sell into: - crossed, the states where economic nexus is established, each with the crossing receipt (revenue or transactions, your value, the threshold, and the overage), - approaching, the states where you are inside the warn band and about to cross, a forward heads-up while you can still get ahead of it, - clear, the states you are safely below for now, - unknown, the states where we do not yet have a validated threshold, flagged for you rather than guessed.
A dated answer you can act on and hand to your accountant, not a maybe.
WHO IT'S FOR
Multi-state e-commerce sellers, SaaS companies, and DTC brands who are past a few hundred thousand in revenue and selling into many states without a tax team watching each threshold, first, and fractional CFOs, bookkeepers, and ops platforms carrying that same exposure across a book of growing clients, second. If your sales cross state lines and nobody is watching the thresholds, this is for you. If you already have a tax team with automated registration in every state, you do not need it.
PRICING (the ladder)
We price the ladder, not a single number, and every number below is a hypothesis we validate with you, not a commitment. - Monitor, a flat monthly subscription, the rolling crossed / approaching / clear report over your own sales feed with the crossing receipts. - Value-metered, scaling with the states you monitor and your volume, once the monitor has caught a crossing you would have missed. - Platform, license the deterministic monitor into a bookkeeping or e-commerce-ops platform carrying many sellers.
IP is licensed, never assigned. The monitor stays ours, the answers are yours. Any step that takes your money is gated and confirmed before it runs, nothing charges silently.
THE PROOF (dogfood)
We run the discipline on ourselves. As AYA starts selling its own products across states, our own sales feed is exactly what this monitor reads, so we are customer zero watching our own nexus with the same evaluator we sell. In this build, the evaluator was exercised offline across the cases that matter: a revenue crossing (over five hundred thousand dollars into California) fired with the correct receipt, a transaction-count crossing (past two hundred orders into Georgia) fired on the count prong, a state that requires both prongs (New York) with only the order count met was correctly held back from crossed and flagged approaching, a state we had no validated threshold for (Arizona) abstained as unknown instead of clear, and a malformed feed failed closed with an error rather than a false all-clear.
HONEST NOTE
Two things are true and worth saying plainly. First, the grouping-and-threshold engine in the middle is new code (no existing capability grouped sales by state against a Wayfair threshold, the tax math we already had is income and capital-gains tax, so we wrote a minimal, fail-closed module for this), and that code is marked for review and not yet running on a live, booted system. Second, and this is the important one, the per-state threshold numbers ship as placeholders that must be validated against each state's own tax authority before you rely on the monitor, because these thresholds change by statute and ruling and a stale number is worse than no number. Nothing here is tax or legal advice. Everything above the pricing is structurally built and unit-verified offline, nothing has been billed, published, or run against a real seller's data, and the pricing figures are hypotheses we intend to test with a first customer.
*This page is a specification. The capability it describes is not built yet, and nothing here is a claim that it runs today.*