Rental Property Cash Flow Analyzer mechanism

Model scope

The standard intended calculation under the stated assumptions is cash_flow = rent - mortgage_payment - taxes - insurance - HOA - rent*vacancy_pct - rent*maintenance_pct - rent*mgmt_fee_pct. The supplied formula is dimensionally invalid because currency amounts are mixed with percentage rates. Vector 2's expected result uses the corrected formula: 383 monthly and 4596 annual.

• The formula subtracts maintenance%, vacancy%, and property_mgmt% as raw numbers instead of converting them to expense amounts, such as rent*maintenance_pct.
• The formula does not define how annual net cash flow is calculated; it should be monthly_net_cash_flow*12 when all inputs are monthly.
• The formula does not define the expense-breakdown pie calculations.
• The claim "after all expenses" is incomplete because the listed formula omits potentially material expenses such as utilities, legal/accounting costs, licenses, repairs beyond the maintenance allowance, and capital expenditures.

Units and conventions

• Rent, mortgage payment, taxes, insurance, and HOA are assumed to be monthly amounts.
• Percentage inputs are assumed to be decimal fractions: 5% must be entered as 0.05, not 5.
• Maintenance, vacancy, and management percentages are assumed to apply to gross monthly rent.
• Annual cash flow is assumed to equal monthly cash flow multiplied by 12.
• Taxes and insurance must be converted to monthly amounts before calculation if supplied annually.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "rent": 2400,
    "mortgage_payment": 1200,
    "taxes": 200,
    "insurance": 100,
    "HOA": 50,
    "vacancy_pct": 0.05,
    "maintenance_pct": 0.08,
    "mgmt_fee_pct": 0.1
  },
  "expected_outputs": {
    "monthly_net_cash_flow": 298,
    "annual_net_cash_flow": 3576,
    "expense_breakdown": {
      "mortgage": 1200,
      "taxes": 200,
      "insurance": 100,
      "HOA": 50,
      "vacancy": 120,
      "maintenance": 192,
      "property_management": 240,
      "total_expenses": 2102
    }
  },
  "working": "Vacancy = 2400*0.05 = 120. Maintenance = 2400*0.08 = 192. Management = 2400*0.10 = 240. Total expenses = 1200+200+100+50+120+192+240 = 2102. Monthly cash flow = 2400-2102 = 298. Annual cash flow = 298*12 = 3576."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

The extreme input overflows JavaScript arithmetic, and the zero-expense boundary makes expense-pie percentages undefined. The specification also lacks a stated branch or validation rule for percentages above 100% and does not clarify whether percentage inputs use percent points or decimal fractions.

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche5/tranche5-results.json
• BOUNDARY_HAZARD_CATALOG.json