APT · SIDE-BY-SIDE COMPARISON · NOTE 03

Buy versus jeonse: compare the financing layer honestly

A deliberately limited comparison showing why principal repayment and interest-only deposit financing should not be labelled as equivalent monthly costs.

INPUT AND EVIDENCE LEDGER

Put the two cases on the same footing.

FieldValueOrigin
Purchase case₩900M price; ₩540M loanIllustrative scenario
Jeonse case₩600M deposit; ₩360M loanIllustrative scenario
Rate4.2%Held constant for illustration
Purchase term30-year equal paymentUser assumption

DECISION READING

Read the gap, not just the winner.

The ₩1.38M gap is not a verdict that jeonse is cheaper: part of the purchase payment builds equity. A useful tool must show cash outflow, interest cost, principal change, capital tied up, and deposit risk as separate rows.

REPRODUCIBLE WORK

The comparison ledger.

CheckFormula or ruleResult
Purchase scheduled payment₩540M, 4.2%, 360 paymentsAbout ₩2,640,693 per month
Jeonse interest layer₩360M × 4.2% ÷ 12About ₩1,260,000 per month
Visible cash-flow gap₩2,640,693 − ₩1,260,000About ₩1,380,693 per month
Classification checkPurchase payment = principal + interestNot equivalent to interest-only cost

SOURCE SNAPSHOT

Official context and the limited role it supports.

SENSITIVITY

Conditions that can reverse the gap.

  • Changing the two loan amounts can reverse the visible cash-flow gap.
  • Deposit return risk and guarantees matter to the jeonse case.
  • Acquisition tax, ownership costs, and expected holding period matter to the purchase case.

HUMAN ACCOUNTABILITY + AI USE RECORD

The owner is accountable; the technical checks were AI-assisted.

The TOOOLBOX site owner authorized the publication scope and remains the correction contact. AI assistance was used for drafting, implementation, arithmetic recomputation, and source-link checks. This record does not claim line-by-line human fact-checking or licensed professional review.

Record ID
TB-APT-03-20260906
Owner role
TOOOLBOX site owner and developer
Technical check date
2026-09-06
Human fact-check
No separate human fact-check recorded
AI use
Drafting, code, arithmetic, and link checks
Correction channel
Public contact page
  1. Recomputed the purchase payment and the jeonse interest-only layer from the declared balances and 4.2% rate.
  2. Confirmed that principal repayment is separated from interest before interpreting the ₩1.38M cash-flow gap.
  3. Checked that deposit risk, guarantees, ownership costs, appreciation, and eligibility remain outside the conclusion.

BOUNDARIES

Claims this comparison cannot support.

  • The jeonse line is an interest-layer illustration, not a quoted loan product.
  • No property appreciation, rent change, or investment return is forecast.
  • Eligibility and legal protections require household-specific verification.

MORE APT DECISION NOTES

Test the result yourself.

This note preserves a dated calculation. Change the inputs in the live workspace, or compare another evidence pattern below. Live source availability and results can differ from the dated example.