Contents
In Korea, a “parking account” is a common term for an accessible account used to hold money temporarily while earning interest. An annual rate of 3% does not mean 3% of your money in 30 days. With ₩5 million held at that fixed rate for 30 days, the illustrative gross interest is about ₩12,329. Applying a simple 15.4% withholding assumption gives about ₩10,430. The amount, period and eligible balance all matter.
- Base example
- ₩5 million · 3% annually · 30 days
- Method
- Simple interest · 365-day year · fixed balance and rate
- Tax assumption
- 15.4% deducted for illustration
- Purpose
- Invented conditions, not a product recommendation
Convert an annual rate into 30 days
The example uses principal × annual rate × days ÷ 365. Enter 3% as 0.03: ₩5,000,000 × 0.03 × 30 ÷ 365 = ₩12,328.77 before tax, or about ₩12,329 rounded to the nearest won.
Multiplying the unrounded amount by 0.846 gives about ₩10,430.14 after the simplified withholding assumption. Actual bank amounts may differ because of daily balances, rate changes, payment rules and rounding or truncation of tax. The calculator is an estimate.
Split the calculation when the balance changes
If the money stays for 15 days at ₩5 million and another 15 days at ₩2 million, do not apply ₩5 million to the full 30 days. Calculate each period separately.
At a constant assumed 3%, the two gross amounts are approximately ₩6,164 and ₩2,466, totalling about ₩8,630. The simplified combined after-tax estimate is ₩7,301. Final calculations use unrounded values.
KakaoBank’s official Safe Box guide is one example of daily interest based on the end-of-day balance. Do not assume every parking account has identical payment dates or terms.
A headline 4% can earn less than 2%
Imagine account A pays 4% on the first ₩1 million and 1% on the remaining ₩4 million, while B pays 2% on the full ₩5 million. Assume all other conditions are equal and A’s rates apply progressively to those portions.
A’s simple annualised gross interest is ₩40,000 + ₩40,000 = ₩80,000, a weighted 1.6%. B produces ₩100,000, or 2%. In this invented comparison, B earns more for this deposit despite its lower headline rate.
Actual products may apply a new band to the excess amount or to the entire balance. Read the product terms before choosing the calculation.
| Measure | A · Headline 4% | B · Flat 2% |
|---|---|---|
| Rate structure | First ₩1m: 4%; excess: 1% | All ₩5m: 2% |
| Weighted annual rate | 1.6% | 2.0% |
| Approx. gross, 30 days | ₩6,575 | ₩8,219 |
| Approx. after withholding | ₩5,563 | ₩6,953 |
Read the conditions beside the rate
Write down the comparison date, base and preferential rates, eligible balance and qualification period. Check requirements such as salary transfers, card spending or new-customer status, and what rate applies if you miss them.
Check payment frequency and withdrawal arrangements too. Interest calculated daily is not necessarily paid daily. If you will use the money soon, ease of access belongs in the comparison.
Separate withholding from deposit protection
The 15.4% figure is an illustrative assumption for ordinary taxable deposits, not a calculation of your final tax liability. Exemptions, residency, tax treaties and account eligibility may change the result for international readers.
The Financial Services Commission announced a ₩100 million protection limit including principal and interest from 1 September 2025. First check whether the product is covered, then read how protected deposits at the same financial institution are aggregated. Do not treat every account as having its own independent ₩100 million limit.
Write down three personal inputs
Use the amount you will deposit, the date you need it again, and the rates with and without the preferential conditions. These let you compare actual amounts rather than only a ranking of headline rates.
If the monthly difference is small, compare the work needed to meet the conditions and the withdrawal process. Check the provider’s current product disclosure before selecting an account.
Frequently asked questions
Why does my bank pay a slightly different amount?
Daily balances, actual day counts, rate changes, reinvestment and rounding or truncation rules may differ. This calculator assumes a fixed balance and rate with simple interest.
Is 3% a rate available to me now?
It is an invented input for teaching the calculation, not a current offer or a guaranteed return.
Summary
Compare the amount deposited, the number of days and any rate limits together. Under the example of ₩5 million at 3% for 30 days, simple interest is about ₩12,329 before tax or ₩10,430 after assumed 15.4% withholding. For real accounts, check daily balances, conditions, payment rules and deposit protection on the same basis.
