The same base salary can produce a different deposit when allowances, adjustments or withholding settings change. Match gross pay before adding up deduction differences.
Gather two payslips
Base salary staying the same does not mean gross pay stayed the same. Compare the pay period, base salary, allowances, gross pay, each deduction and the actual deposit. This guide diagnoses changes rather than listing new contribution rates.
| Record | What to find |
|---|---|
| Two payslips and deposits | Pay periods, totals and transferred amounts |
| Contract and hours | Allowances, overtime and unpaid time |
| Insurance reports and adjustments | Reported bases, regular contributions and reconciliation |
| Withholding settings | Dependents, selected ratio and additional tax adjustments |
Worked example: gross pay stays at KRW 3 million
This fictional statement is a comparison exercise, not a calculation from actual reported insurance bases or official rates. Gross pay is KRW 3,000,000 in both months. Assume the following deduction amounts.
| Deduction | First month | Next month | Increase |
|---|---|---|---|
| Pension | KRW 142,500 | KRW 142,500 | KRW 0 |
| Regular health insurance | KRW 107,850 | KRW 107,850 | KRW 0 |
| Regular long-term care | KRW 14,170 | KRW 14,170 | KRW 0 |
| Employment insurance | KRW 27,000 | KRW 27,000 | KRW 0 |
| Income tax | KRW 50,000 | KRW 60,000 | KRW 10,000 |
| Local income tax | KRW 5,000 | KRW 6,000 | KRW 1,000 |
| Separate insurance reconciliation | KRW 0 | KRW 120,000 | KRW 120,000 |
| Total deductions | KRW 346,520 | KRW 477,520 | KRW 131,000 |
| Take-home pay | KRW 2,653,480 | KRW 2,522,480 | −KRW 131,000 |
Example · Check the reduced deposit
- Deduction increase: 10,000 + 1,000 + 120,000 = KRW 131,000.
- Take-home change: 2,522,480 − 2,653,480 = −KRW 131,000.
- Regular insurance contributions stayed the same in this example. A rate increase does not explain the entire difference.
Compare in this order
- Match the pay periods. A partial month or unpaid period is not directly comparable with a full month.
- Check allowances and gross pay as well as base salary. Distinguish a payment change from its tax-free classification.
- Subtract the first month’s amount from the next month’s for each deduction. Ask payroll to split regular and reconciliation amounts if combined.
- Gross-pay change minus deduction change should equal the take-home change.
- Match take-home pay to the bank deposit. Check separate transfers, payment dates and installments when relevant.
Questions for each changed deduction
| Changed item | Question |
|---|---|
| Pension | Did the reported standard monthly income or effective period change? |
| Health and long-term care | Regular payment or reconciliation? Which year, period and installment? |
| Employment insurance | What remuneration and adjustment formed the deduction? |
| Income and local tax | Did dependents, the withholding ratio, table conditions or year-end adjustment change? |
| Other deductions | What is the basis, applicable period and relevant consent or rule? |
Health insurance uses the reported/calculated monthly remuneration base, which is not always this month’s taxable pay. NHIS EDI guidance describes a reconciliation statement for checking finalized contributions. Ask how the statement maps to the payslip’s adjustment.
The National Tax Service describes choosing 80%, 100% or 120% of the simplified-table tax. If the assumed base tax is KRW 50,000, 100% gives KRW 50,000 and 120% gives KRW 60,000. This changes monthly prepayment, not the final yearly liability by that same ratio.
Use the interactive sample for the right purpose
Select pay and deduction items in the payslip tool to read their calculation steps, then find the corresponding items on your own statement. The tool uses fictional wages and illustrative income tax; it does not accept your actual payroll to determine an exact contribution. Use employer and agency records for personal reported bases and reconciliation amounts.
Estimates and reference information, not legal or tax advice. Even a small difference should be checked for a different calculation base before being attributed to rounding.
A concrete payroll question
“Gross pay is unchanged, but take-home pay fell by KRW 131,000. I see increases of KRW 10,000 in income tax, KRW 1,000 in local tax and KRW 120,000 in reconciliation. Please confirm the basis and period of each, whether it is one-off, and whether it will continue next month.”
Replace the example amounts with your own differences. You do not need to send identification numbers or original payslips to korWork. A calculator issue can be reported with fictional inputs and reproduction steps.