Rental Property Cash Flow Analyzer

Inspectable records

Ledger state

The current ledger marks this instrument verified with errata that must be applied at binding time.

Area

Finance, Economics & Business (educational only — never individualized investment, tax, or legal advice)

Tranche

tranche-5

Evidence ID

t5-166

Ledger rows

1

No ledger note is attached.

Review findings

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.

Formula and scope findings

• 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.

Unit assumptions

• 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.

Boundary hardening

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.

Errata and corrections

Tranche errata

Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

{
  "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."
}

Related workflows

No source-defined multi-instrument workflow membership is recorded.

Sources and evidence

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

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