# US Sales Tax Economic Nexus Checker

> 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.

## Facts

- Endpoint: POST https://x402-agent-tools.nerolabs.workers.dev/rules/us-sales-tax-nexus?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-22
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/us-sales-tax-economic-nexus-checker-e8665adb
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_vpuwmAVHzVMbwBoLexz7T

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability us-sales-tax-economic-nexus-checker-e8665adb -d '<json body>'
```

Example prompt: Check which US states I need to register in for sales tax — I sold $612,000 into California with 3,400 transactions and $85,000 into Texas with 900 transactions over the last 12 months, and those figures include marketplace sales through Amazon.

## When to prefer this

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.

## Known failure modes

- 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

## How this service works

Pay-per-call tools for AI agents, 31 in all: read web pages and RSS feeds, OCR, PDF text, transcription; email, phone and domain checks; UK, Irish and Polish company lookups and UK risk reports; website contacts, tech stack and SEO audits; PageSpeed; AI review, job post and row enrichment; data cleaning, joins, dedupe and diffs; US and EU compliance rules. No account or API key: pay each call in USDC on Base over x402.

## 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.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "date": {
   "type": "string",
   "description": "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": {
   "enum": [
    "last_12_months",
    "previous_calendar_year",
    "current_calendar_year"
   ],
   "type": "string",
   "description": "What period the figures cover: last_12_months (default), previous_calendar_year or current_calendar_year (year to date)."
  },
  "sales_by_state": {
   "type": "array",
   "items": {
    "type": "object"
   },
   "description": "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": {
   "type": "boolean",
   "description": "True to also list every sales tax state the seller did not report sales for. Default false."
  },
  "includes_marketplace_sales": {
   "type": "boolean",
   "description": "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."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "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_coun
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/us-sales-tax-economic-nexus-checker-e8665adb/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-agent-tools.nerolabs.workers.dev](https://www.zero.xyz/host/x402-agent-tools.nerolabs.workers.dev/llms.txt)