How much principal remains after a partial repayment?
A bank receipt does not necessarily reduce the principal by its full amount.
Eligible debtor costs and unpaid interest can absorb part or all of a payment before principal decreases.
This ledger follows dated receipts on a single Korean debt and separates the amounts applied to costs, interest and principal.
It uses Korean Civil Act rules checked in 2026 and an explicitly chosen calculation convention.
Compare receipts with actual principal reductions
Borrowers can check how much a payment reduced principal; creditors can check whether subsequent interest used the remaining principal.
The same ledger can help family members reconcile a private loan before discussing a debt acknowledgment or settlement.
Outputs organize supplied facts and assumptions: they do not establish the other party's consent or determine a court outcome.
Article 479: costs, then interest, then principal
Korean Civil Act Article 479 sets the default sequence when a payment is insufficient to extinguish the relevant costs, interest and principal.
Costs are applied first, followed by interest and then principal.
A receipt may therefore leave principal unchanged, and that principal continues to determine subsequent simple interest.
An asserted cost does not automatically qualify for priority allocation.
Using the default sequence
Choose the default when there is no separately verified allocation agreement.
Verify who owes each cost and its established amount before including it.
Articles 476 and 477 concern designation and allocation between multiple debts; this single-debt tool does not determine those priorities or proportional allocations.
Using a bilateral agreement
Supreme Court case 2009Da12399 recognizes that a special agreement, or an established implied agreement, can support a different order.
The tool offers all six permutations of the three buckets.
A unilateral transfer note stating principal does not by itself establish the agreement; review the other party's position and evidence before marking it verified.
What the opening balances and inputs mean
End-of-day opening principal, interest and costs
Opening principal is the principal still unpaid at the end of the opening date.
Opening interest is interest already accrued and unpaid through that date, rather than future interest.
Entering the original loan without accounting for earlier payments overstates the opening balance.
Opening costs must likewise be eligible unpaid debtor costs existing at that point.
If you enter events on the opening date, do not pre-apply those same-day receipts or costs to the opening balances.
Applicable annual rate and cutoff
Enter the rate supported by your contract, agreement or court records.
The initial 0% is an unverified starting input, not an automatic finding that no interest is owed.
The technical 0–100% input range is not a lawful rate limit.
The cutoff includes events through the end of that date and cannot precede the opening date.
The calculator does not choose statutory interest rates or decide when a delay-damages rate begins.
Established costs and dated additions
Eligible costs are not every expense actually incurred by a creditor.
Under the principles in 2008Da61172, check contractual or statutory debtor liability and relevant cost-amount determinations.
Do not put an unconfirmed lawyer quote or expected litigation bill into priority costs.
Record later costs on their applicable recognition dates, without duplicating opening costs.
Simple interest on the remaining principal
Interval interest = previous principal × annual rate / 100 × days / divisor
Exclude the opening day and include each receipt day.
A principal reduction on a receipt date changes interest from the following day.
Neither costs nor unpaid interest are capitalized, so the tool does not compound interest.
Civil Act Article 157 provides an initial-day exclusion principle and a midnight exception; this tool specifically starts from an end-of-day opening balance.
Choose fixed 365 days every year, or actual-year 365 days and 366 days in leap years.
The actual-year option splits accrual by the calendar year of each interest-bearing day.
Crossing a leap year can therefore change interest for the same elapsed period.
Contractual first-day inclusion, monthly interest, other proration conventions and rate changes require a separate reconciliation.
These day-count choices are calculation assumptions, rather than a finding about your contract.
Whole-won allocation and fractional interest
The calculation carries fractional interest across events instead of discarding it at each row.
Only the whole-won part of cumulative unpaid interest is available for allocation from an integer-won receipt.
For example, 0.6 KRW of interest displays as zero whole won plus a separate 0.6 KRW fraction.
If another 0.6 KRW accrues, one won becomes allocable and 0.2 KRW remains carried.
Splitting same-day receipts or inserting a cost row does not erase those fractions.
A reference balance is not a final settlement determination
The main total adds remaining principal, whole-won interest and costs; the fractional interest appears separately.
A zero whole-won balance with a remaining fraction still requires agreement on final rounding.
This is the tool's consistent convention, not a universal statutory truncation rule.
Excess receipts remain unapplied and do not automatically pay future costs or offset fractional interest.
Step-by-step use
- Collect the loan document and bank records, then establish end-of-day opening balances.
Keep interest already accrued through that day separate from principal.
- Verify opening costs, the applicable rate and the day-count convention.
Use Unknown for missing evidence, or Assumed for an intentional planning assumption.
- Choose Article 479's default sequence or a bilateral agreed order.
Check that the selected order applies throughout this ledger.
- Add later established costs and actual receipts with dates, amounts, evidence status and optional notes.
Arrange same-day receipts in their actual input sequence.
- Calculate and review principal reduction, interest applied, unapplied money and pending evidence.
Save TXT or print the review sheet, then reconcile each row against the other party's records.
Worked example: two receipts leave KRW 8 million principal
This fictional example is not a market rate or an actual contract.
At the end of 2026-01-01, principal is KRW 10,000,000, opening interest is zero and eligible costs are KRW 100,000.
Use an annual rate of 3.65%, a fixed 365-day divisor and costs → interest → principal.
Receive KRW 1,110,000 on 2026-01-11 and KRW 1,009,000 on 2026-01-21, then observe the balance at the end of 2026-01-31.
Fictional 3.65% ledger showing interval interest and receipt allocations in KRW| Date / event | Interest accrued | To costs | To interest | To principal | Principal left |
|---|
| 2026-01-11 receipt | 10,000 | 100,000 | 10,000 | 1,000,000 | 9,000,000 |
| 2026-01-21 receipt | 9,000 | 0 | 9,000 | 1,000,000 | 8,000,000 |
| 2026-01-31 cutoff | 8,000 | 0 | 0 | 0 | 8,000,000 |
Connecting payments with the current balance
Each interval is 10 days; newly accrued interest totals KRW 27,000.
Of the total KRW 2,119,000 received, KRW 100,000 goes to costs, KRW 19,000 to interest and KRW 2,000,000 to principal.
The last KRW 8,000 of interest remains unpaid, so the whole-won reference balance is KRW 8,008,000.
Subtracting all receipts directly from the original principal would miss those allocations.
Reading Unknown, Assumed and Verified outputs
Unknown
Evidence has not been verified.
Entering a number does not remove the item from the pending list.
Zero costs also require verification that no eligible costs remain.
Assumed
A planning assumption substitutes for established facts.
Change the order or rate to compare outcomes, while retaining the Assumed label.
Share that label with anyone reviewing the result.
Verified
The user states that supporting evidence has been checked.
When every included item is verified, the tool marks inputs verified.
This does not mean a court or the other party has confirmed the debt.
Any included Unknown or Assumed input leaves the output as an arithmetic preview with pending items.
A future receipt or cost is excluded from the current balance, so its evidence status does not change current verification status.
A useful settlement discussion includes both the amount and the facts that still require checking.
Later costs, same-day events and future receipts
- A later eligible cost enters on its recognition date.
It never rewrites an earlier payment to reverse a principal reduction.
If the proper cost date is disputed, verify the underlying determination before relying on the ledger.
- Additional costs precede receipts on the same date, while receipts follow input order.
The day's interest appears at the first event and subsequent same-day events have zero elapsed days.
If the cost actually arose after a receipt, this day-level assumption may not fit the transaction.
- Rows after the cutoff are retained in the original inputs and export but excluded from the balance.
Do not treat a planned payment as a received payment.
Update the cutoff and evidence after actual receipt.
- Unapplied money is the part left after all currently allocable whole-won balances are paid.
It does not establish an automatic refund or a binding advance payment against future obligations.
Practical scenarios and scope boundaries
Reconciling a private loan
Use actual receipt records where sending and receipt dates differ, or repayments were irregular.
Compare opening balances and each principal allocation before signing a debt acknowledgment.
Keep different loan documents and different creditors in separate reconciliations instead of combining them into one debt.
Disputed rates, costs or claim scope
For unlawful excess-interest allocation and refunds, use the separate interest overcharge refund calculator and its distinct rules.
Do not combine pre-litigation and post-service or post-judgment rates into one fixed-rate ledger.
Rent termination thresholds, auction distributions, court deposits, setoff, variable rates and allocation between multiple debts are outside this tool's scope.
Before saving or printing
Keep evidence and assumptions with the figures
The TXT includes original inputs, evidence states, notes, excluded future rows, allocations, fractional interest, assumptions and official sources.
The printable review uses the same information so another reader can understand the calculation.
Use short document references in notes rather than sensitive account or identity numbers.
Supported dates are 1900-01-01 through 2026-12-31; the tool does not retroactively verify the law governing historical transactions.
Each amount is integer KRW up to 1 trillion, with up to 60 receipts and 24 additional cost rows.
If the rate or allocation order changes, reconcile the three balances at the change date and start a separate ledger, recording any fractional settlement separately.
When receipt dates, costs or consent are disputed, share an evidence-review draft instead of treating the output as a finally established claim.
Frequently asked questions
Does a transfer note saying principal change the order?
A unilateral note does not by itself verify an agreement changing the default.
Review consent and supporting records; leave agreement evidence Unknown if unresolved.
Use the default calculation as a comparison for discussion.
Must I verify costs when the amount is zero?
Zero can mean either no costs or missing information.
Choose Verified only after checking that no eligible costs remain.
Do not enter an estimate as established costs and thereby postpone principal reduction.
Does existing unpaid interest earn more interest?
This ledger calculates simple interest only on remaining principal.
Opening interest and costs do not earn new interest.
Separate delay damages on an interest debt or a lawful compounding agreement need their own review.
What if the rate changes midway?
One annual rate and one allocation order apply to this ledger.
Reconcile balances through the change date and start a separate ledger, documenting fractional settlement.
Dates alone do not trigger an automatic litigation-rate change.
Do two receipts on the same day charge interest twice?
The second same-day event has zero elapsed days and adds no new interest.
Receipts follow input order and fractions remain carried.
If costs arise that day, check whether the assumed costs-first event timing matches the facts.
Does a zero whole-won balance mean full settlement?
Check separate fractional interest and pending evidence.
A remaining 0.6 KRW fraction, for example, requires a final rounding agreement even if the whole-won total is zero.
Inputs verified does not establish legal discharge or a waiver of the claim.
Can I combine loans or calculate unlawful-interest refunds?
Allocation between multiple debts requires separate review under Articles 476 and 477.
Unlawful-interest repayment and mandatory principal allocation follow distinct rules in the refund calculator.
Do not mix unconfirmed costs or auction distributions into this ledger.
How should I share the ledger with the other party?
Compare opening-balance records, rate evidence, the allocation agreement and cost determinations with the TXT or printout.
Keep Unknown and Assumed labels, excluded future rows and unapplied amounts visible.
Resolve disputed items, update the cutoff and calculate again.
Official sources, rule dates and your next action
Sources were checked on 2026-10-16.
Direct National Law Information OPEN API queries verified current Korean Civil Act ID 001706, MST 284415, Act No. 21454, promulgated and effective 2026-03-17, including Articles 157, 473, 476, 477 and 479.
Historical maximum rates and historical litigation rates appearing in old judgments are not current rate defaults in this calculator.
Recheck effective dates, lawful rates, cost liability and determinations, actual receipt dates, same-day timing and fractional settlement when law or contracts change.
Return to the calculator and enter your receipts, then save remaining principal together with pending evidence for a debt acknowledgment or settlement discussion.