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US Sales Tax Economic Nexus Checker
x402
US Sales Tax Economic Nexus Checker is a paid API for AI agents from x402-agent-tools.nerolabs.workers.dev, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-22).
Determines which US states a remote seller must register in to collect sales tax based on economic nexus thresholds, given sales and transaction counts per state.
Price / call$0.003
Success—
StatusUnknown
How this service works
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Output
A structured JSON response with a plain-English verdict, plus three lists: states where the seller must register (with threshold details, what counts, measurement period, registration deadline, revenue department source URL, and a breakdown of the seller's figures), states close to the threshold (80%+ of limit), and states under the threshold. Each entry includes the state name, threshold amount, measurement period, marketplace sales treatment, and a link to the primary government source.
Example use cases
E-commerce seller nexus audit
“I'm a remote seller and want to know which states I've crossed the economic nexus threshold in. My last 12 months of sales include $750,000 and 6,200 transactions into Texas, $310,000 and 1,800 transactions into Florida, and $95,000 and 600 transactions into Ohio. All figures include Amazon marketplace sales — tell me where I need to register.”
Pre-expansion compliance check
“We're about to start shipping into several new states and need to know if our projected sales will trigger sales tax registration. For the previous calendar year we had $480,000 into New York with 2,100 transactions and $210,000 into Washington with 950 transactions, not including marketplace sales. Which states are we over or close to the threshold?”
Marketplace seller exemption analysis
“I sell exclusively through Amazon and Etsy — can you check my economic nexus status for sales tax? I have $900,000 in sales and 5,000 transactions into California and $430,000 and 2,200 transactions into Illinois over the last 12 months. My sales figures include all marketplace-facilitated sales.”
Technical details
Endpoint
POSThttps://x402-agent-tools.nerolabs.workers.dev/rules/us-sales-tax-nexus?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need to determine US state sales tax registration obligations for a remote seller based on economic nexus thresholds. It is specifically designed for the Wayfair-era economic nexus rules, handles marketplace facilitator exclusions per state, and links each determination to the primary government source — making it ideal for compliance automation, pre-expansion checks, or ongoing monitoring. Prefer it over a generic tax API when you need state-by-state threshold comparisons with sourced regulatory details rather than just a tax rate lookup.
Side effects
- Missing or malformed sales_by_state array returns a validation error
- Invalid state codes in the sales data may be rejected or ignored
- Date parameter outside the range of known threshold history may return no matching rule
- Providing figures for a period that doesn't match the state's measurement period generates a depends_on warning rather than a definitive verdict
- Extremely large arrays or malformed JSON objects in items may cause a 400 error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| date | string | The date to check the rules on, YYYY-MM-DD. Defaults to today. Thresholds changed in several states; past dates use the rule then in force. |
| period | string | What period the figures cover: last_12_months (default), previous_calendar_year or current_calendar_year (year to date). |
| sales_by_state | array | One item per state the seller ships into: {"state":"CA","sales":612000,"transactions":3400}. Optional per item: marketplace_sales and marketplace_transactions (the part made through marketplace facilitators like Amazon), retail_sales (sales excluding sales for resale), taxable_sales (sales excluding exempt sales). Dollars are US dollars. |
| show_all_states | boolean | True to also list every sales tax state the seller did not report sales for. Default false. |
| includes_marketplace_sales | boolean | True (default) if the sales and transactions figures include sales made through marketplace facilitators. Many states exclude those sales when testing a remote seller's threshold. |
Output
Schema · Response
{
"type": "json",
"example": {
"date": "2026-10-21",
"verdict": "Register in 1 state: CA.",
"disclaimer": "Information, not legal advice. Built from primary government sources (linked per figure); check the source before acting on a close call.",
"_example_note": "Real output, trimmed: long lists cut to their first items and long text shortened.",
"must_register": [
{
"name": "California",
"note": "AB 147 passed 25 April 2019 and applied the $500,000 test to sales from 1 April 2019; district taxes from 25 April 2019. Retailers must also...",
"state": "CA",
"result": "Over the threshold on the figures given (SAFE answer): register to collect sales tax.",
"source": "https://www.cdtfa.ca.gov/industry/wayfair.htm",
"threshold": "$500,000 in sales",
"depends_on": [
"Your figures cover the last 12 months; California measures previous or current calendar year (crossing in either counts). Re-run with figure..."
],
"register_by": "Register and start collecting straight after the sale that takes total sales over $500,000 (CDTFA example: threshold passed on 6 July, regis...",
"what_counts": "Total combined sales of tangible personal property for delivery in California by the retailer and all related persons, including nontaxable...",
"your_figures": {
"period": "last_12_months",
"sales_counted": 612000,
"transactions_counted": 3400
},
"marketplace_sales": "Counted: a marketplace seller must include its marketplace-facilitated sales together with its direct sales.",
"measurement_period": "previous or current calendar year (crossing in either counts)",
"percent_of_sales_threshold": 122,
"verified_on_primary_source": true,
"percent_of_transaction_threshold": null,
"register_by_date_if_crossed_today": "2026-10-21"
}
],
"under_threshold": [
{
"name": "Texas",
"note": "Remote sellers may use a single local use tax rate instead of each local rate (not available to marketplace providers). To stop, a seller ne...",
"state": "TX",
"result": "Under the threshold.",
"source": "https://comptroller.texas.gov/taxes/sales/remote-sellers.php",
"threshold": "$500,000 in sales",
"what_counts": "Total Texas revenue: gross revenue from taxable and nontaxable sales of goods and services into Texas, including separately stated handling,...",
"your_figures": {
"period": "last_12_months",
"sales_counted": 90000,
"transactions_counted": 150
},
"marketplace_sales": "Counted: include all sales, marketplace sales too, even when the marketplace collects (stated as of 1 April 2020).",
"measurement_period": "any rolling 12 month period",
"percent_of_sales_threshold": 18,
"verified_on_primary_source": true,
"percent_of_transaction_threshold": null
}
]
}
}Tags
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