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This guide shows how to build insurance underwriting rules that assess risk, calculate premiums, and determine policy terms.

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What you’ll build

An underwriting decision that:
  • Evaluates applicant risk factors
  • Calculates risk-adjusted premiums
  • Determines coverage eligibility
  • Applies regulatory constraints
Want to skip ahead? Download the completed decision and import it directly.

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Decision flow

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Example: Auto insurance quote

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Input data

{
  "applicant": {
    "age": 28,
    "yearsLicensed": 10,
    "accidentsLast5Years": 0,
    "violationsLast3Years": 1,
    "creditTier": "good"
  },
  "vehicle": {
    "year": 2022,
    "make": "Toyota",
    "model": "Camry",
    "value": 28000,
    "safetyRating": 5,
    "antiTheft": true
  },
  "coverage": {
    "type": "full",
    "deductible": 500,
    "state": "CA"
  }
}

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Step 1: Driver risk assessment

Score driver risk factors:
Inputs
Outputs

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Step 2: Driving history

Assess accidents and violations:
Inputs
Outputs

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Step 3: Vehicle risk

Assess vehicle factors:
Inputs
Outputs

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Step 4: Calculate base premium

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Step 5: Coverage and deductible adjustments

Inputs
Outputs

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Step 6: Credit-based adjustment

Inputs
Outputs

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Step 7: Final premium calculation

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Step 8: Eligibility decision

Inputs
Outputs

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Output structure

{
  "decision": "approve",
  "annualPremium": 1247.50,
  "monthlyPremium": 103.96,
  "riskFactors": {
    "driver": 1.0,
    "history": 1.0,
    "vehicle": 0.9,
    "credit": 1.0,
    "combined": 0.9
  },
  "coverage": {
    "type": "full",
    "deductible": 500,
    "liability": 100000
  }
}

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Regulatory compliance

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State-specific rules

Inputs
Outputs

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Best practices

Audit all decisions — Log every factor for regulatory review. Version rating tables — Track when rates change for policy renewals. Handle edge cases — New drivers, antique vehicles, rideshare use. Test extensively — Validate against known good quotes.