Check the money behind a used-car installment quote
A contract principal is not always the amount available to buy the vehicle.
Withheld charges, required products and a final balloon can change the economic cost even when two advertised monthly payments look similar.
This Korea-based 2026 calculator compares two actual quotes in KRW using the amounts provided, dated repayments, initial cash and monthly payment concentration.
It helps a household review its own, a spouse’s or an adult child’s proposed contract before requesting an itemized written explanation.
What this comparison answers
- How much financing benefit was actually provided, including direct dealer payments?
- What economic effective annual rate follows from the actual payment dates?
- How much cash is needed at acquisition after a deposit already paid?
- Which month exceeds the household’s installment budget, including any balloon?
This tool does not use a credit score to predict approval or a lender’s offered rate.
Examples are fictional rather than market averages, available products or lending promises.
The economic XIRR result is not the statutory actual annual installment fee rate and does not determine whether a contract is unlawful.
Documents and input amounts to prepare
- Cash vehicle price and acquisition costs: record the vehicle’s price V without financing and confirmed taxes, registration, insurance and other acquisition expenses.
Separate acquisition costs paid in cash A from acquisition costs financed within dealer payment D, denoted T; never enter the same expense in both fields.
- Principal and disbursement statement: obtain the contractual principal, actual payment to the dealer, actual cash received by the buyer and financing charges withheld from the principal.
- Products and separately paid charges: distinguish a required product included in the dealer payment from a product paid separately in cash, and record a separately paid financing fee only once.
- Agreed down payment and deposit already paid: the agreed down payment includes the deposit already paid.
The deposit is a subset, not an additional acquisition charge.
- Disbursement date and complete payment schedule: include every repayment date and amount, plus the final balloon if it is outside the advertised monthly amount.
Both quotes use Korean won (KRW).
The calculator does not estimate acquisition tax, insurance premiums or a universal dealer fee.
Use actual documents and align the cost coverage of the two quotes before interpreting differences.
An unknown amount should be confirmed rather than silently entered as zero.
Separate principal, actual proceeds and withholding
Actual financing provided
G = dealer disbursement D + buyer cash received C.
A direct payment to the dealer is financing provided even though it never appears in the buyer’s bank account.
Using only buyer cash or the face principal can misstate the benefit financed.
Principal reconciliation
Δ = contractual principal P − D − C − withheld charge W.
An absolute difference above KRW 1 requires clarification of payment destinations or charge classification.
An unexplained difference pauses the rate ranking; it does not establish misconduct or a recoverable loss.
Avoid deducting withholding twice. If KRW 1,000,000 was withheld from a KRW 10,000,000 principal and KRW 9,000,000 was paid to the dealer, actual proceeds are already KRW 9,000,000.
Do not subtract the withheld charge again to produce KRW 8,000,000.
Only a genuinely separate cash payment belongs in the separate upfront fee field.
M is a required financing product included within dealer disbursement D.
Acquisition costs financed within D, denoted T, are also separated from vehicle funding, but remain in economic benefit because they fund actual acquisition expenses.
M + T must not exceed D; do not also enter M as separately paid product U or T as cash acquisition costs A.
This is an explicit economic classification assumption, not a legal finding that a cost counts as interest.
Economic financing cost and dated XIRR
Cash-flow definitions
- G: actual financing provided; M: required product within the dealer payment; T: acquisition costs financed within D
- F: separate upfront financing fee; U: separate upfront required product
- N = G − M − F − U: net economic benefit on the disbursement date
- K = total scheduled payments − N: total economic financing cost
- Principal-based repayment difference = total scheduled payments − P
The initial cash flow is +N on the disbursement date and each repayment is a negative cash flow on its actual scheduled date.
For cash flow CF and actual elapsed days d from disbursement, XIRR finds the annual rate r that makes the following sum zero.
Σ CF ÷ (1 + r)^(d ÷ 365) = 0
The displayed economic effective annual rate is r × 100%.
It uses actual elapsed days with a fixed 365-day denominator, including across a leap year.
Changing payment dates can change the result even when total repayments stay the same.
This annual compounding measure need not match a monthly rate multiplied by 12, a quoted interest rate or a statutory actual annual installment fee rate.
No annual rate is produced when net economic benefit is nonpositive or there is no valid positive repayment.
A cash flow outside the supported numerical range requires review.
If repayments are below economic proceeds, a negative economic rate can result; recheck missing payments and any discount arrangement before interpreting it.
Initial cash, deposit credit and total net outlay
Let V be the vehicle cash price, A separate cash acquisition costs, T acquisition costs financed within the dealer payment, H the agreed down payment including any paid deposit, and E the deposit already paid.
Net vehicle payment L = D − M − T.
The down-payment reconciliation is V − H − L: a positive amount indicates an unexplained vehicle funding shortfall, while a negative amount calls for an excess-payment explanation rather than an automatic refund assumption.
Total initial cash = max(0, max(0, V − L) + A + F + U − C)
Remaining acquisition cash = max(0, total initial cash − E)
Funding beyond agreed vehicle balance = max(0, G − max(0, V − H))
Buyer cash left after acquisition = max(0, C − (max(0, V − L) + A + F + U))
Total net outlay = V + A + T + K
The initial-cash calculation assumes that buyer cash C is available to meet acquisition costs.
T has already been paid through financing, so it is not added again to initial cash; it is separately included in total net outlay to preserve all acquisition costs.
If buyer cash arrives later or is restricted, the cash actually needed on delivery day may be higher.
The deposit E is already part of initial cash and must not be added to total net outlay again.
Review the documentation if E exceeds H or exceeds the calculated initial cash.
Funding beyond the agreed vehicle balance is a description of the current disbursement, not a new loan approval or freely available profit.
If net vehicle payment exceeds the vehicle price, ask where the excess went and how it is settled.
Do not assume that all apparent excess financing is usable household cash.
How to enter and review two quotes
- Prepare written quotes A and B for the same vehicle and a consistent acquisition-cost scope.
Replace every fictional example with the actual documented amount.
- Enter each disbursement date, vehicle cash price, principal, actual dealer payment and actual buyer cash.
Ask for a payment statement when an amount is unknown.
- Separate withholding, separately paid fees and the two product categories.
Resolve principal and down-payment reconciliation differences before relying on a ranking.
- Enter every dated repayment and balloon.
A generated monthly schedule still needs checking against the first payment, adjusted month-end dates and final payment in the contract.
- Set a common monthly installment budget and calculate.
Compare annual rate, total financing cost, initial cash, peak monthly payment and balloon together.
- Save the review and send the unresolved items as written questions to the dealer or finance provider.
Calculate again after changing an input so the result reflects the latest quote.
Each monetary input accepts whole KRW from zero to KRW 1,000,000,000, and a payment ledger supports at most 240 rows.
Use valid dates within 2000–2100 and repayments after disbursement within ten years.
This single-disbursement model does not cover additional drawdowns, multiple financing receipts, early repayment, arrears, refunds or mixed currencies.
Worked example: a one-year contract with withholding
This fictional example disburses on 2026-01-01 and has one KRW 11,000,000 payment on 2027-01-01.
It is deliberately simple to show the effect of withholding; it is not a current product or a market quote.
Fictional Korean used-car financing inputs and results in KRW| Item | Amount or result |
|---|
| Vehicle V / cash acquisition costs A / financed costs T | KRW 12,000,000 / 1,000,000 / 0 |
| Principal P / dealer D / withholding W | KRW 10,000,000 / 9,000,000 / 1,000,000 |
| Agreed down payment H / paid deposit E | KRW 3,000,000 / 1,000,000 |
| Buyer cash C / products M and U / fee F | All KRW 0 |
| Net benefit N / total repayments | KRW 9,000,000 / 11,000,000 |
| Financing cost K / principal-based difference | KRW 2,000,000 / 1,000,000 |
| Economic annual rate / fee-free sensitivity | About 22.222222% / 10% |
| Total initial cash / remaining acquisition cash | KRW 4,000,000 / 3,000,000 |
| Total net outlay | KRW 15,000,000 |
Over exactly one 365-day year, 11,000,000 ÷ 9,000,000 − 1 is about 22.222222%.
If the withheld KRW 1,000,000 had instead also been provided, the same repayment against KRW 10,000,000 proceeds would imply 10%.
The latter is a sensitivity assumption, not a promised fee refund.
The paid deposit reduces remaining acquisition cash from KRW 4,000,000 to KRW 3,000,000 and is not added again to the KRW 15,000,000 net outlay.
Fictional example with financed acquisition costs
Assume vehicle price V is KRW 12,000,000 and both principal P and dealer payment D are KRW 13,000,000, including acquisition costs T of KRW 1,000,000.
Cash acquisition costs A, down payment H, buyer cash C, withholding, required products and separate fees are all zero, with KRW 14,300,000 repaid after 365 days.
Net vehicle payment is KRW 12,000,000, matching the vehicle price without an excess-payment warning.
The KRW 13,000,000 economic benefit gives KRW 1,300,000 financing cost, a 10% economic annual rate, zero initial cash and KRW 14,300,000 total net outlay.
This arithmetic example isolates financed acquisition costs; it does not promise that an actual contract has no deposit or cash expenses.
Read fee sensitivities and monthly budget together
Without required products
Keep every repayment unchanged and replace the initial benefit with N + M + U.
For example, KRW 10,000,000 provided, KRW 1,000,000 included product and KRW 500,000 separately paid product imply KRW 8,500,000 net benefit; the product-free assumption uses KRW 10,000,000.
Product cancellation, refund entitlement and unchanged loan terms require separate confirmation.
Without financing fees
Keep the repayment ledger unchanged and use N + F + W at disbursement.
This assumes withholding W was also actually provided; it does not describe the current bank receipt.
The two sensitivities isolate different cost groups, so their rate differences should not simply be added.
Monthly burden groups every scheduled payment and balloon in the same calendar month.
Inspect the peak amount, its month and any excess over the common monthly budget.
The period average divides total repayments by the calendar-month difference from disbursement to the last payment, with a minimum denominator of one month.
Months without payments remain in that span; a low average does not remove a large final balloon.
The budget comparison includes only the entered installments and balloons.
Fuel, charging, parking, maintenance and future insurance are outside that comparison and need a separate household reserve.
A lower annual rate can still require more initial cash, a larger final payment or a longer commitment.
Practical scenarios and review limits
- Reviewing a family member’s contract: reconcile actual proceeds and the final payment before focusing on the advertised monthly figure.
Separate the deposit already paid from additional cash needed at acquisition.
- Two similar monthly payment quotes: compare fees, required products, dates and duration.
The lowest annual rate and lowest total outlay may belong to different quotes.
- Disbursement above the agreed vehicle balance: identify whether it is buyer cash, a product payment or another settlement.
It is not automatically a financial gain.
- Unexplained principal or down-payment difference: obtain missing payment destinations and itemized charges first.
The annual-rate ranking remains on hold while reconciliation issues remain.
Correct invalid dates, dates before disbursement, negative or nonfinite amounts and inputs outside the supported limits.
Blank or unknown values are not evidence of a zero cost.
A contract involving further advances, arrears, early settlement, refunds or currency conversion needs a fuller cash-flow analysis beyond this model.
Frequently asked questions
1. Does a high economic annual rate prove illegality?
No.
The economic cash-flow classification and actual-day XIRR are distinct from statutory installment-fee calculations and their applicability.
Use the result to organize contract questions rather than to determine a legal violation.
2. Should I include money paid directly to the dealer?
Yes.
A documented direct dealer payment is financing provided for the purchase even if the buyer never received it in a bank account.
Confirm it against the lender’s disbursement statement and the dealer’s receipt.
3. How is withholding different from a separate fee?
Withholding reduces the amount actually disbursed from principal.
A separate fee is an additional cash payment outside those proceeds.
Record a cost only once and do not subtract withholding again from already reduced proceeds.
4. Do I add the paid deposit to the down payment?
The agreed down payment already includes the paid deposit.
Subtract the deposit from total initial cash to find remaining acquisition cash; do not add it again to total net outlay.
5. What if the balloon is outside the monthly installment?
Enter it as a separate balloon row with its actual date and amount.
It is included in total repayments and combined with other payments in the same month for the peak-budget check.
Do not assess affordability using an average that omits it.
6. Can I actually borrow on the product-free sensitivity terms?
The sensitivity keeps repayments fixed and changes only the assumed initial benefit.
It does not establish cancellation, a refund or unchanged borrowing terms.
Request revised written terms and a disbursement statement.
7. Are taxes and dealer fees calculated automatically?
No.
Use confirmed actual amounts because vehicle, tax and transaction circumstances differ, separating cash acquisition costs A from acquisition costs T financed within D without duplication.
There is no invented national flat dealer fee or assumed average borrowing rate.
8. Should I choose the quote with the lowest annual rate?
Compare total financing cost, net outlay, initial cash, peak monthly payments and balloon as well.
Different terms and timing can change the household decision.
If reconciliation issues remain, even the rate ranking is withheld pending clarification.
Official Korean sources and 2026 review date
Sources were reviewed on 2026-11-12 through the National Law Information OPEN API and current public article pages.
They support checking contract disclosures and itemized charges, not treating economic XIRR as a statutory compliance result.
- Installment Transactions Act, Article 6: Act No. 21906, current public article effective 2026-09-08, API MST289407.
Check the cash and installment prices, installment timing, actual annual fee rate, deposit and other required contract items.
- Enforcement Decree, Article 5: Presidential Decree No. 36416, effective 2026-07-01, MST287001.
The statutory actual annual fee rate follows a separate Annex 1 method; this calculator implements neither that statutory formula nor a legal ceiling test.
- Enforcement Rule of the Automobile Management Act, Article 122: Ministry Ordinance No. 1167, effective 2026-10-02, MST290943.
Confirm itemized actual brokerage, registration-agency, storage and price-appraisal charges and their disclosures rather than assuming one universal fee.
The API detail header for MST289407 mixed in a future 2027-09-09 effective version, so the Article 6 text was cross-checked against the current public article page.
Future provisions are not treated as currently effective.
Recheck subsequent amendments, actual product requirements and allocation, duplicated costs and revised payment dates before relying on a later contract review.
Turn the comparison into written questions
Request the vehicle cash price, financing paid to each recipient, withholding, separate fees, itemized products and the full dated repayment schedule for both quotes in the same format.
Ask the dealer or finance provider to explain reconciliation differences and acquisition cash requirements, then calculate again after confirming the final balloon.
Use the Auto Loan Calculator to estimate standard repayments from a quoted rate, or the Used Car Total Cost Calculator for ownership expenses.
This page checks a proposed contract’s actual cash-flow assumptions and helps identify the next questions to confirm.