Card installment plans let you decide at the time of purchase to repay the amount in installments. Installment conversion is a service that changes the repayment method after a lump-sum purchase. With revolving credit, you agree to carry part of the balance over to the next month. When choosing, check the total fees and the conditions for completing repayment.
The revolving credit calculations below are examples provided in a KB Kookmin Card disclosure reviewed on February 23, 2026.
Comparison of Installment Plans, Installment Conversion, and Revolving Credit
The key difference among the three methods is how the repayment schedule is set. Installment plans and installment conversion divide the principal over the selected period. Revolving credit repays an amount based on the payment ratio and carries over the remaining principal.
| Comparison item | Card installment plan | Post-purchase installment conversion | Revolving credit |
|---|---|---|---|
| When selected | When purchasing a product or service | After a lump-sum purchase | Applied to eligible charges after enrollment |
| Unit of application | Transaction made using an installment plan | Eligible lump-sum transaction | Eligible charges specified in the agreement |
| Repayment method | Repaid in installments over the selected period | Repaid in installments over the converted period | Balance carried over after repayment based on the agreed payment ratio |
| End of repayment | Ends after normal payment through the specified installment | Ends after normal payment through the specified installment | Varies depending on the balance, additional spending, and payment ratio |
| Cost | Interest-bearing or conditionally interest-free | Individual fees, subject to separate waiver conditions | Fees on the principal carried over |
| Main items to check | Interest-free eligibility and number of installments | Application deadline and total fees | Minimum payment and carried-over balance |
Here, installment conversion is a service that converts a lump-sum charge afterward. Do not confuse it with splitting a payment among several cards at a store. The official name for revolving credit is an agreement to carry over part of the payment amount. You can also check the basic structure in the Financial Services Commission's comparison of revolving credit and installment plans.
A man checks card payment and repayment details on his smartphone.
How Do Fees and Interest-Free Benefits Differ?
You cannot conclude that installment conversion is always more expensive than an installment plan. The applicable rate varies depending on the user, the usage period, and other factors. Compare the total fees under the same repayment amount and period.
An installment plan divides the principal and adds fees to the billed amount. The available periods vary by card issuer and merchant. The same maximum installment period does not apply to every card.
| Displayed condition | Meaning | What to check |
|---|---|---|
| Interest-free installments | Installment fees are waived if the conditions are met | Eligible cards, merchants, number of months, and promotion period |
| Partially interest-free installments | Fees are waived only for certain installments | Installments you must pay fees on and total fees |
| Conversion of a lump-sum payment to installments | Payment schedule changed after purchase | Whether the interest-free promotion available at purchase applies |
| Annual fee rate | Cost benchmark shown as an annual percentage | Amount billed based on the actual balance and usage period |
An interest-free benefit offered at the time of purchase does not automatically apply to a later conversion. However, installment conversion may have separate fee waiver conditions. The Samsung Card installment conversion guide provides conditions for waiving fees on certain installments. Check the conditions that apply to you on the application screen.
Whether a transaction is interest-free and whether it earns points are also separate matters. The Shinhan Card points guide states that interest-free installments are excluded from point accrual. Check your card's product description for the criteria used to count spending toward the previous month's performance requirement.
Revolving Credit Calculation Example
The actual amount debited under revolving credit is not simply the eligible principal multiplied by the payment ratio. This is because fees are added separately. You may also have to pay billed amounts that are not eligible for revolving credit.
The KB Kookmin Card disclosure calculates the amount under the following conditions. The annual rate of 17% is for illustration. Do not interpret it as the rate currently applied to you.
| Calculation condition | Disclosure example |
|---|---|
| Principal carried over from the previous month | KRW 500,000 |
| New eligible spending for the current month | KRW 300,000 |
| Agreed payment ratio | 50% |
| Annual fee rate | 17% |
| Carryover period | 30 days |
| Charges not eligible for revolving credit | KRW 100,000 |
- Eligible principal repaid this month: (KRW 500,000 + KRW 300,000) × 50% = KRW 400,000
- Carryover fee: KRW 500,000 × annual rate of 17% × 30 days ÷ 365 days = KRW 6,986 according to the disclosure
- Total payment this month: KRW 400,000 + KRW 6,986 + KRW 100,000 = KRW 506,986
- Eligible principal remaining after payment under the agreement: KRW 400,000
In this example, 50% does not mean paying only half of the total billed amount. KRW 400,000 in principal will still remain next month. The calculation conditions and amounts are based on the KB Kookmin Card revolving credit disclosure.
Selection Criteria by Situation
Your selection should be based on a repayment schedule you can manage, rather than how much this month's bill will decrease. Dividing money you have already spent leaves payment obligations for the following months. Consider future card charges as well.
| Current situation | Method to consider | Decision criteria |
|---|---|---|
| You have not yet made the purchase and plan to repay in installments | Choose installments at purchase | Interest-free conditions and an affordable monthly payment |
| You made a lump-sum purchase and can set a repayment period | Check whether installment conversion is available | Eligible transaction, application deadline, and total fees |
| You temporarily lack funds for payment | Ask the card issuer about available payment methods | Effective date and funds for later repayment |
| You already have a revolving credit balance | Consider reducing additional carryovers and repaying early | New spending, remaining principal, and cost of full repayment |
| You may also struggle to obtain the required payment amount next month | Request repayment counseling from the card issuer | Available adjustments other than repeated carryovers |
Revolving credit can help address a short-term shortage of funds if payments are made according to the terms. However, the carried-over balance may grow if new card charges are also added. The Financial Supervisory Service warns that long-term use may affect creditworthiness. Related information appears in the consumer alert dated December 12, 2023.