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refinance-breakeven

refinance-breakeven

【数据与研究】Compute the month a refinance actually starts saving money — payment delta, breakeven month, and total interest on both paths including the term-reset trap. Use when asked should I refinance, when does a refi break even, compare my loan to a refi offer, or is this refinance worth the closing costs. Produces the breakeven analysis with both interest t…

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技能说明

GitHub

name: refinance-breakeven description: "Compute the month a refinance actually starts saving money — payment delta, breakeven month, and total interest on both paths including the term-reset trap. Use when asked should I refinance, when does a refi break even, compare my loan to a refi offer, or is this refinance worth the closing costs. Produces the breakeven analysis with both interest totals, the if-you-sell-before-month-N warning, and the cases where the breakeven math lies."

Refinance Breakeven Skill

"Lower monthly payment" and "saves money" are different claims, and lenders profit from the confusion. This skill computes when a refinance genuinely breaks even — and names the two standard ways the simple math lies: the term reset that trades a lower payment for more total interest, and the cash-out that relabels borrowing as saving.

What This Skill Produces

  • The breakeven analysis — payment delta, upfront costs, the month cumulative savings pass them
  • Both interest totals — keep vs refi, side by side, costs included
  • The honest verdict — refinance / don't / refinance-but-shorter-term, with the reason

Required Inputs

Ask for these if not provided:

  • Current loan: remaining balance, rate, months left
  • The offer: rate, term, closing costs, points (if any)
  • The horizon: how long the user realistically expects to keep this home/loan — breakeven beyond the horizon is a loss dressed as a saving
  • Cash-out? — if the refi increases the balance, say so; the analysis changes character

Programmatic Helper

python3 scripts/refinance_breakeven.py --balance 380000 --rate 6.9 --months-left 336 \
    --new-rate 5.6 --new-term 360 --closing 6500
python3 scripts/refinance_breakeven.py --json-input refi.json --json

Standard amortization, simple-savings breakeven (cumulative payment delta vs upfront costs). The script prints the term-reset warning itself when the new term extends the payoff date. Not modeled — and say so: reinvestment of savings, tax deductibility, ARM resets.

Framework: When Breakeven Math Lies

The lieThe tellThe honest comparison
Term reset26 years left → "new 30-year loan"Total interest both paths (the script prints it) — or price the refi at the same remaining term
Cash-out gravity"…and take $40k out while rates are good"That's a new loan decision; analyze it separately at its own rate
Points seductionLower rate via pointsPoints go into upfront cost; breakeven moves — recompute, don't eyeball
Horizon blindnessBreakeven month 38, moving in ~2 yearsIf sell-month < breakeven month, the refi is a donation to the lender

Output Format


Refinance Analysis: [loan]

The Numbers

[Script output: payments, delta, breakeven month, both interest totals, term-reset warning if applicable]

The Verdict

[Refinance / Don't / Refinance at a shorter term] — because [breakeven vs horizon, and the interest-total comparison in one sentence].

What Would Change the Answer

[Rate threshold where the verdict flips; the horizon below which it flips; whether a same-term refi dominates the offered one.]

Educational model, not financial advice — verify with a licensed professional before acting on it.


Quality Checks

  • Breakeven month is compared against the user's stated horizon, not shown in isolation
  • Total interest on both paths appears whenever the term changes
  • Points are inside the upfront cost, not footnoted
  • The verdict names its reason in one sentence
  • The disclaimer line appears in the artifact

Anti-Patterns

  • Do not equate a lower payment with saving money — the term reset is the whole trap
  • Do not fold a cash-out into the breakeven — it's a separate borrowing decision
  • Do not report a breakeven month without the sell-before-month-N warning
  • Do not present the model's output without what it doesn't model

Example Trigger Phrases

  • "Should I refinance?"
  • "Does a refi break even?"
  • "Compare my loan to a refi offer."
  • "Is this refinance worth the closing costs?"
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