Closing Costs & Cash-to-Close Estimator

Inspectable records

Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Area

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

Tranche

tranche-4

Evidence ID

t4-044

Ledger rows

1

No ledger note is attached.

Review findings

The core arithmetic is valid only under the explicit assumptions listed above. The instrument should require a fee mode, define the percentage base and input convention, specify treatment of credits and prepaid items, and add deposits or clearly state that they are excluded. The honest-label warning is appropriate: this is an educational rough estimate and not a Loan Estimate, Closing Disclosure, GFE, or individualized financial, tax, or legal advice.

Formula and scope findings

• The arithmetic relationship cash_to_close = down_payment + closing_costs - credits is standard for a rough estimate, but the specification does not explicitly define down_payment = purchase_price × down_percent or loan_amount = purchase_price - down_payment.
• The percentage-fee base is described as the loan, but the input specification does not explicitly require or define the derived loan amount; the exact ambiguity is whether the fee percentage applies to the purchase price or the loan amount.
• The formula does not state whether earnest-money deposits, prior payments, financed fees, lender credits, seller credits, prepaid taxes, insurance, and escrow deposits are included or subtracted. Therefore it is not a complete general cash-to-close formula.
• The specification does not define whether percentage inputs are entered as percentage points, such as 2.5, or decimals, such as 0.025. It also does not require selecting exactly one fee mode: percentage-based or itemized.

Unit assumptions

• All monetary inputs and outputs are assumed to be in the same currency; the test vectors use USD.
• down_percent and closing_cost_rate_percent are interpreted as percentage points and divided by 100; for example, 20 means 20%, not 0.20.
• For percentage-based closing costs, loan_amount is assumed to equal purchase_price minus down_payment, and the fee is closing_cost_rate_percent ÷ 100 × loan_amount.
• For itemized fees, closing_costs equals the sum of all listed fee amounts, with no duplicate inclusion of the same charge.
• credits are currency amounts subtracted from the calculated cash requirement.
• These assumptions exclude earnest-money deposits or other amounts already paid unless the implementation explicitly adds them as inputs.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

An extreme but numerically valid JavaScript input produces 2e308, which overflows to Infinity. The estimator should reject, cap, or otherwise handle non-finite results rather than displaying Infinity as a cash-to-close amount.

Errata and corrections

No applied erratum is attached to this unique-name record.

Inspectable example

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

{
  "inputs": {
    "currency": "USD",
    "purchase_price": 400000,
    "down_percent": 20,
    "closing_cost_mode": "percent_of_loan",
    "closing_cost_rate_percent": 3,
    "credits": 2500
  },
  "expected_outputs": {
    "down_payment": 80000,
    "loan_amount": 320000,
    "closing_costs": 9600,
    "credits": 2500,
    "cash_to_close": 87100
  },
  "working": "down_payment = 400000 × 20 ÷ 100 = 80000; loan_amount = 400000 - 80000 = 320000; closing_costs = 320000 × 3 ÷ 100 = 9600; cash_to_close = 80000 + 9600 - 2500 = 87100."
}

Related workflows

Sources and evidence

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

• VERIFIED_LEDGER.json · VERIFIED_CLEAN
• evidence-tranche4/tranche4-results.json
• BOUNDARY_HAZARD_CATALOG.json