Input schema (JSON)
{
"type": "object",
"$schema": "https://json-schema.org/draft/2020-12/schema",
"required": [
"axis"
],
"properties": {
"axis": {
"type": "object",
"required": [
"parameter"
],
"properties": {
"max": {
"type": "number"
},
"min": {
"type": "number"
},
"steps": {
"type": "integer",
"maximum": 50,
"minimum": 2,
"description": "With min and max: number of evenly spaced values (2 to 50)."
},
"values": {
"type": "array",
"items": {
"type": "number"
},
"maxItems": 50,
"minItems": 2,
"description": "Explicit values to test (2 to 50)."
},
"parameter": {
"enum": [
"homePrice",
"downPayment",
"closingCosts",
"renovations",
"mortgageRate",
"mortgageTerm",
"interestOnlyPeriod",
"propertyTaxRate",
"homeInsurance",
"maintenanceRate",
"hoa",
"appreciationRate",
"adjustmentYear",
"adjustedValue",
"sellingCosts",
"monthlyRent",
"rentIncreaseRate",
"rentersInsurance",
"investmentReturn",
"householdIncome",
"federalTaxRate",
"stateTaxRate",
"standardDeduction"
],
"type": "string",
"description": "Input to vary."
}
},
"additionalProperties": false
},
"base": {
"type": "object",
"properties": {
"hoa": {
"type": "number",
"maximum": 20000,
"minimum": 0,
"description": "HOA dues, held flat. Unit: USD per month. Default: 0."
},
"homePrice": {
"type": "number",
"maximum": 50000000,
"minimum": 10000,
"description": "Purchase price of the home. Unit: USD. Default: 800000."
},
"downPayment": {
"type": "number",
"maximum": 100,
"minimum": 0,
"description": "Down payment as a percentage of the price (20 = 20%). Unit: % of price. Default: 20."
},
"monthlyRent": {
"type": "number",
"maximum": 100000,
"minimum": 0,
"description": "Rent for a comparable home in year 1. Unit: USD per month. Default: 3500."
},
"renovations": {
"type": "number",
"maximum": 5000000,
"minimum": 0,
"description": "One-time renovation spending at purchase; it does not add to the home value. Unit: USD. Default: 0."
},
"closingCosts": {
"type": "number",
"maximum": 1000000,
"minimum": 0,
"description": "One-time closing costs paid at purchase. Unit: USD. Default: 20000."
},
"filingStatus": {
"enum": [
"single",
"marriedJoint",
"headOfHousehold"
],
"type": "string",
"description": "Federal filing status used to pre-fill the tax inputs. Unit: enum. Default: marriedJoint."
},
"mortgageRate": {
"type": "number",
"maximum": 30,
"minimum": 0,
"description": "Mortgage interest rate (6.5 = 6.5%). Unit: % per year. Default: 6.5."
},
"mortgageTerm": {
"type": "integer",
"maximum": 40,
"minimum": 1,
"description": "Loan term in years. The analysis horizon is always 30 years. Unit: years. Default: 30."
},
"mortgageType": {
"enum": [
"amortizing",
"interestOnly"
],
"type": "string",
"description": "'amortizing' pays principal and interest; 'interestOnly' pays interest only for interestOnlyPeriod years, then amortizes the balance over the remaining term (a balloon if the period covers the whole term). Unit: enum. Default: amortizing."
},
"sellingCosts": {
"type": "number",
"maximum": 20,
"minimum": 0,
"description": "Selling costs subtracted from the headline buy result at year 30. Unit: % of sale price. Default: 6."
},
"stateTaxRate": {
"type": "number",
"maximum": 30,
"minimum": 0,
"description": "State marginal rate applied the same way. Unit: %. Default: 5."
},
"adjustedValue": {
"type": "number",
"maximum": 100000000,
"minimum": 0,
"description": "Home value to use in adjustmentYear; 0 disables the adjustment. Unit: USD. Default: 0."
},
"homeInsurance": {
"type": "number",
"maximum": 100000,
"minimum": 0,
"description": "Homeowner insurance premium, held flat. Unit: USD per year. Default: 2400."
},
"adjustmentYear": {
"type": "integer",
"maximum": 30,
"minimum": 0,
"description": "Year in which the home value is reset to adjustedValue; 0 disables it. Unit: year (0 = none). Default: 0."
},
"federalTaxRate": {
"type": "number",
"maximum": 60,
"minimum": 0,
"description": "Federal marginal rate applied to itemized deductions above the standard deduction. Unit: %. Default: 22."
},
"householdIncome": {
"type": "number",
"maximum": 100000000,
"minimum": 0,
"description": "Household income; with filingStatus it pre-fills federalTaxRate and standardDeduction unless those are given explicitly. Unit: USD per year. Default: 200000."
},
"maintenanceRate": {
"type": "number",
"maximum": 10,
"minimum": 0,
"description": "Maintenance as a percentage of the current home value. Unit: % of home value per year. Default: 1."
},
"propertyTaxRate": {
"type": "number",
"maximum": 10,
"minimum": 0,
"description": "Property tax as a percentage of the current home value. Unit: % of home value per year. Default: 1.25."
},
"appreciationRate": {
"type": "number",
"maximum": 30,
"minimum": -20,
"description": "Annual home value appreciation (3 = 3%). Unit: % per year. Default: 3."
},
"investmentReturn": {
"type": "number",
"maximum": 30,
"minimum": -20,
"description": "Effective annual return on invested savings for both households (7 = 7%). Unit: % per year (effective annual). Default: 7."
},
"rentIncreaseRate": {
"type": "number",
"maximum": 30,
"minimum": -10,
"description": "Annual rent growth (3 = 3%). Unit: % per year. Default: 3."
},
"rentersInsurance": {
"type": "number",
"maximum": 20000,
"minimum": 0,
"description": "Renter insurance; it grows with rent. Unit: USD per year. Default: 300."
},
"standardDeduction": {
"type": "number",
"maximum": 1000000,
"minimum": 0,
"description": "Standard deduction the itemized deductions must exceed to save tax. Unit: USD. Default: 32200."
},
"interestOnlyPeriod": {
"type": "integer",
"maximum": 40,
"minimum": 0,
"description": "Interest-only years; only used when mortgageType is interestOnly. Unit: years. Default: 10."
}
},
"description": "Inputs held fixed during the sweep.",
"additionalProperties": false
},
"secondAxis": {
"type": "object",
"required": [
"parameter"
],
"properties": {
"max": {
"type": "number"
},
"min": {
"type": "number"
},
"steps": {
"type": "integer",
"maximum": 50,
"minimum": 2,
"description": "With min and max: number of evenly spaced values (2 to 50)."
},
"values": {
"type": "array",
"items": {
"type": "number"
},
"maxItems": 50,
"minItems": 2,
"description": "Explicit values to test (2 to 50)."
},
"parameter": {
"enum": [
"homePrice",
"downPayment",
"closingCosts",
"renovations",
"mortgageRate",
"mortgageTerm",
"interestOnlyPeriod",
"propertyTaxRate",
"homeInsurance",
"maintenanceRate",
"hoa",
"appreciationRate",
"adjustmentYear",
"adjustedValue",
"sellingCosts",
"monthlyRent",
"rentIncreaseRate",
"rentersInsurance",
"investmentReturn",
"householdIncome",
"federalTaxRate",
"stateTaxRate",
"standardDeduction"
],
"type": "string",
"description": "Input to vary."
}
},
"description": "Optional second input for a grid.",
"additionalProperties": false
},
"oneTimeCosts": {
"type": "array",
"items": {
"type": "object",
"required": [
"year",
"amount",
"appliesTo"
],
"properties": {
"year": {
"type": "integer",
"maximum": 30,
"minimum": 1,
"description": "Year of the cost, 1 to 30."
},
"amount": {
"type": "number",
"maximum": 100000000,
"minimum": 0,
"description": "Amount in USD."
},
"reason": {
"type": "string",
"maxLength": 80,
"description": "Label, e.g. \"New roof\"."
},
"appliesTo": {
"enum": [
"buy",
"both"
],
"type": "string",
"description": "'buy' = a house expense only the buyer pays (the renter invests that amount); 'both' = a general expense both households pay from their investments."
}
},
"additionalProperties": false
},
"maxItems": 20,
"description": "Up to 20 one-time costs."
}
},
"additionalProperties": false
}