DECISION READING
The threshold that changes the reading.
The advertised discount is economically meaningful, but only for borrowers who actually qualify. APT should show the base-rate result first and treat a preferential rate as a verified alternative, not a default assumption.
REPRODUCIBLE WORK
Test both sides of the boundary.
10-year base
₩300M at 4.90% for 120 months
₩3,167,322 monthly10-year floor
₩300M at 3.90% for 120 months
₩3,023,117 monthly10-year difference
Base − floor
₩144,205 monthly; ₩17.3M across 120 payments50-year difference
₩1,404,938 − ₩1,197,135
₩207,803 monthly; ₩124.7M across 600 paymentsSENSITIVITY
Move the input and watch the boundary.
- A partial discount produces a result between the two displayed endpoints.
- A smaller principal reduces the absolute won difference proportionally.
- Term eligibility affects both the payment and the usefulness of the comparison.
INPUT AND EVIDENCE LEDGER
Values held constant for this test.
| Field | Value | Origin |
|---|---|---|
| Principal | ₩300,000,000 | Controlled comparison input |
| 10-year pair | 4.90% base / 3.90% maximum-discount floor | HF release |
| 50-year pair | 5.20% base / 4.20% maximum-discount floor | HF release |
| Discount qualification | Not assumed | Must be verified by HF |
SOURCE SNAPSHOT
Verify the threshold in the official rule.
OWNER AUTHORIZATION + VERIFICATION RECORD
One accountable operator and a reproducible check record.
The TOOOLBOX site owner authorized this publication scope and remains the correction contact. The checks below were completed during preparation with AI-assisted implementation; they are an audit record, not a claim of licensed professional review.
- Review ID
- TB-APT-11-20260902
- Owner role
- TOOOLBOX site owner and developer
- Release scope
- Owner-authorized · 2026-09-02
- Correction channel
- Public contact page
- Verified that the release describes the lower range as conditional.
- Recomputed four amortization schedules from the declared principal.
- Checked that the article never labels the discount floor as an offer.
BOUNDARIES
What the threshold does not decide.
- Maximum discounts are conditional and cannot be inferred from income alone.
- The calculation does not reproduce HF underwriting.
- No claim is made about rates after September 2026.
MORE APT DECISION NOTES
Compare another evidence pattern.
The related notes deliberately use different questions, data states, and editorial forms.