Track every state's sales tax nexus threshold before you cross it

A brand that sells on Shopify, Amazon, Walmart and to wholesale buyers ships into most US states. Each state with a sales tax decides for itself when a remote seller has to register, and the rules differ in four ways: the dollar amount, whether a number of transactions also counts, the period measured, and whether your marketplace sales are part of the total. Nobody checks all of that by hand every month. This recipe does the counting and tells your finance owner early. It is one page of our automation library.

What does each state's rule look like?

The table below is the core of the tracker: one row per state, every cell read today on that state's own revenue department page. We kept only states where the page we could read states all four parts of the rule, including how a seller's marketplace sales count. New York, Florida, Illinois, Georgia and Ohio are left out for that reason, not because they do not matter; add them once your adviser confirms their marketplace treatment.

Two details change what you count. California's Wayfair FAQ says its total may include nontaxable sales, such as sales for resale, so wholesale counts there. Texas defines total Texas revenue as taxable and nontaxable sales into Texas, including sales for resale and separately stated handling, transportation and installation fees. Keep gross amounts, refunds and fees in separate columns so each state's rule can pick the right measure.

Timing matters too. Washington's page says a seller that did not meet the threshold last year starts collecting on the first day of the month that begins at least 30 days after it meets it. Texas says a seller that sells only through a marketplace provider that certifies it collects the tax for the seller does not need a Texas permit. Those are exactly the details the alert should carry to your adviser.

Does Shopify already track this?

Partly. Shopify's Tax liability insights page shows states marked Action required, where potential liability is identified, and Monitoring, where Shopify sales have reached at least 80% of a state's threshold (checked October 30, 2026). It counts net sales, meaning sales less refunds, shipping and tax, from transactions within Shopify and imported orders with a valid shipping address. Marketplace transactions count only where state law requires it, and the page is not available when Shopify manages your US sales tax.

That is a good starting signal for the Shopify channel, and the 80% mark is a sensible alert level. It cannot see Amazon orders, Walmart orders or wholesale invoices that never pass through Shopify. Shopify's own US tax reference also differs from two state pages above today: it lists California marketplace sales as excluded, and Pennsylvania as a twelve-month rolling period with marketplace sales included (checked October 30, 2026). When a tool and the state's page disagree, the tracker follows the state page and flags the difference for your adviser.

What data does each channel provide each month?

The sources behind that table: Shopify's orders export columns; Amazon's order report types, which list the All Orders report with ship-state for MFN and FBA, and tax report types, which say the US Sales Tax Report cannot be requested or scheduled and is generated in the Tax Document Library; Walmart's Marketplace and WFS payments report with Ship to State; and Walmart's payments report guide with the withheld-tax amount types (all checked October 30, 2026).

How is the running total calculated?

Every order becomes one row with its channel, ship-to state, date, amounts and a flag for whether a marketplace facilitator collected the tax. For each state, the rules table says which rows count and over which window. Then:

Measured sales (state) = sum of counted amounts shipped to the state inside its measurement window

Ratio (state) = the larger of measured sales ÷ sales threshold and transaction count ÷ transaction threshold

The window follows the state: the current and previous calendar year for California, Washington and New Jersey (alert on whichever is higher), the last 12 calendar months for Texas, and the calendar year for Pennsylvania. The transaction test applies only in states that have one; New Jersey's is an either-or test, so the larger ratio decides.

The 60% and 80% levels are illustrative starting points; your finance owner sets the real ones. Shopify's own Monitoring status starts at 80%, which is why we use it for Alert.

What does a month's run look like?

An illustrative example, not a client result. A brand sells on Shopify, Amazon and Walmart, and to a few wholesale buyers. In the October run, the tracker shows these measured amounts per state, each under that state's own rule.

Two rows show why the rules table matters. In Pennsylvania the marketplace collected the tax on the Amazon and Walmart sales, so they are left out; counting them would show $114,000 and a false Crossed. In New Jersey the dollar total is only 45% of $100,000, but 233 separate transactions pass the 200 test. A tracker that only watched dollars would miss it. The finance owner gets three alerts with the rows behind them and takes them to the tax adviser.

Where does it sit next to your other finance workflows?

The tracker reuses data other workflows already move. Our marketplace payouts to QuickBooks and Xero recipe books the tax a marketplace collected into a clearing account; the same order rows tell this tracker which sales a facilitator handled. Our daily sales report to Slack already pulls orders from every channel each morning, so adding ship-to state to that pull feeds the monthly run. For wholesale, our wholesale customer application queue collects resale certificates, which matter for how a sale is taxed even when it still counts toward a threshold.

The merchant of record glossary entry explains that marketplace facilitator laws cover only sales made through the marketplace, not sales on your own website or to wholesale buyers. The tracker exists for that gap.

Which tool should run it?

Our Zapier vs Make vs n8n comparison covers how each tool counts work.

Who builds sales tax nexus trackers?

Ecomsellertool builds workflow automation on your own store, marketplace and accounting accounts; we have built software on Amazon's seller APIs since 2017. For a nexus tracker we write the rules table and alert levels with your finance owner first, then connect each channel's order data and the alerts. Your tax adviser keeps every tax decision. Send a project brief, or see how our workflow automation service works.

The building blocks are work we have shipped:

• One view of orders across channels. For Beezboard we built a profit and loss statement tailored to specific marketplaces, and an orders view from Amazon SP-API report data covering both Amazon and non-Amazon channels, with Amazon SQS used for faster updates on order activity and fee changes.
• Merging reports into period totals. For Lavley we identified the reports needed, merged data from several Amazon sources, and built analytics by brand, ASIN, year, quarter, month and week, the same period roll-ups a nexus window needs.

Get your nexus tracker built