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Tax rates you can trace to the source.

Sales tax at a street address and state income tax, by API. Every rate comes back with its official source, the dates it applies and when we last checked it. We calculate; we don't file. Works alongside Stripe.

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Denver, CO sales tax on $100

1437 Bannock St, Denver, CO 80202 · $100.00 · collecting tax in Colorado

Total9.15% · $9.15
Request
curl https://api.asizor.com/v1/tax/sales \
  -H "x-api-key: $ASIZOR_KEY" \
  -H "content-type: application/json" \
  -d '{"address":"1437 Bannock St, Denver, CO 80202","amount":100,"nexus_states":["CO"]}'
Raw JSON response
{
  "total": {
    "reason": null,
    "exact": true,
    "rate": {
      "max": 0.0915,
      "min": 0.0915
    },
    "tax": {
      "max": 9.15,
      "min": 9.15
    }
  },
  "query": {
    "address": "1437 Bannock St, Denver, CO 80202",
    "on": "2026-10-19",
    "amount": 100,
    "nexus_states": [
      "CO"
    ],
    "geocode_precision": "membership",
    "customer_type": "B2C"
  },
  "components": [
    {
      "reason": null,
      "source": {
        "version": "Colorado_Jurisdiction_Codes_Rates_July-Dec2026.xlsx",
        "url": "https://tax.colorado.gov/sites/tax/files/documents/Colorado_Jurisdiction_Codes_Rates_July-Dec2026.xlsx",
        "freshness": "live_source",
        "effective_from": "2026-07-01",
        "effective_to": null,
        "verification": {
          "status": "verified",
          "last_verified_at": "2026-10-19T02:54:18Z"
        }
      },
      "one_of": null,
      "jurisdiction": {
        "id": "CO-state",
        "name": "Colorado",
        "state": "CO",
        "level": "state",
        "fips": "08"
      },
      "rate": 0.029,
      "applies": "yes",
      "possible_rates": null,
      "tax": 2.9,
      "taxability": "taxable",
      "district": null,
      "taxable": 100
    },
    {
      "reason": null,
      "source": {
        "version": "Colorado_Jurisdiction_Codes_Rates_July-Dec2026.xlsx",
        "url": "https://tax.colorado.gov/sites/tax/files/documents/Colorado_Jurisdiction_Codes_Rates_July-Dec2026.xlsx",
        "freshness": "live_source",
        "effective_from": "2026-07-01",
        "effective_to": null,
        "verification": {
          "status": "verified",
          "last_verified_at": "2026-10-19T02:54:18Z"
        }
      },
      "one_of": null,
      "jurisdiction": {
        "id": "CO-city-0820000",
        "name": "Denver city",
        "state": "CO",
        "level": "city",
        "fips": "0820000"
      },
      "rate": 0.0515,
      "applies": "yes",
      "possible_rates": null,
      "tax": 5.15,
      "taxability": "taxable",
      "district": null,
      "taxable": 100
    },
    {
      "reason": null,
      "source": {
        "version": "Colorado_Jurisdiction_Codes_Rates_July-Dec2026.xlsx",
        "url": "https://tax.colorado.gov/sites/tax/files/documents/Colorado_Jurisdiction_Codes_Rates_July-Dec2026.xlsx",
        "freshness": "live_source",
        "effective_from": "2026-07-01",
        "effective_to": null,
        "verification": {
          "status": "verified",
          "last_verified_at": "2026-10-19T02:54:18Z"
        }
      },
      "one_of": null,
      "jurisdiction": {
        "id": "CO-special-08031-0820000-CD",
        "name": "Scientific and Cultural Facilities District sales tax",
        "state": "CO",
        "level": "special",
        "fips": "08031-0820000-CD"
      },
      "rate": 0.001,
      "applies": "yes",
      "possible_rates": null,
      "tax": 0.1,
      "taxability": "taxable",
      "district": {
        "type": "CD",
        "jurisdiction_codes": [
          "010006"
        ]
      },
      "taxable": 100
    },
    {
      "reason": null,
      "source": {
        "version": "Colorado_Jurisdiction_Codes_Rates_July-Dec2026.xlsx",
        "url": "https://tax.colorado.gov/sites/tax/files/documents/Colorado_Jurisdiction_Codes_Rates_July-Dec2026.xlsx",
        "freshness": "live_source",
        "effective_from": "2026-07-01",
        "effective_to": null,
        "verification": {
          "status": "verified",
          "last_verified_at": "2026-10-19T02:54:18Z"
        }
      },
      "one_of": null,
      "jurisdiction": {
        "id": "CO-special-08031-0820000-RTD",
        "name": "Regional Transportation District sales tax",
        "state": "CO",
        "level": "special",
        "fips": "08031-0820000-RTD"
      },
      "rate": 0.01,
      "applies": "yes",
      "possible_rates": null,
      "tax": 1,
      "taxability": "taxable",
      "district": {
        "type": "RTD",
        "jurisdiction_codes": [
          "010006"
        ]
      },
      "taxable": 100
    }
  ],
  "environment": "production",
  "disclaimer": "Informational only; verify with your tax professional.",
  "jurisdictions": [
    {
      "id": "CO-state",
      "name": "Colorado",
      "state": "CO",
      "level": "state",
      "fips": "08"
    },
    {
      "id": "CO-county-08031",
      "name": "Denver County",
      "state": "CO",
      "level": "county",
      "fips": "08031"
    },
    {
      "id": "CO-city-0820000",
      "name": "Denver city",
      "state": "CO",
      "level": "city",
      "fips": "0820000"
    },
    {
      "id": "CO-special-08031-0820000-CD",
      "name": "Scientific and Cultural Facilities District sales tax",
      "state": "CO",
      "level": "special",
      "fips": "08031-0820000-CD"
    },
    {
      "id": "CO-special-08031-0820000-RTD",
      "name": "Regional Transportation District sales tax",
      "state": "CO",
      "level": "special",
      "fips": "08031-0820000-RTD"
    }
  ],
  "notes": []
}

Real API response from Oct 19, 2026. Informational only; verify with your tax professional.

Coverage, published.

Select a state to see what's covered, how many test cases check it, and the official publications they come from.

50 of 51 jurisdictions golden-tested, including four states with no statewide sales tax. Not covered yet: Alaska.

46 golden-tested 4 no statewide tax 1 not covered

Golden-tested means a published rate matches its source. It isn't a guarantee about your tax position.