What cash does corporate interim tax compare?
Korean corporate interim tax is an advance payment of part of the corporate tax for a fiscal year.
A company that earned a large profit in the previous year but experienced weaker first-half results may face a working-capital shortage if it simply pays using the previous results.
This calculator compares the prior-year assessment method with the actual first six months of interim accounts and shows method availability, exemption candidates and the cash needed at the first deadline.
It is intended for small-company owners and accounting staff preparing half-year books or sending documents to a Korean tax professional.
Separating credits, reductions, withholding and occasional assessments helps prevent errors caused by simply halving last year’s final payment.
After reviewing the comparison, check the Hometax interim-tax lookup against the actual exemption and return, and prepare financial statements and tax-adjustment schedules when interim accounts are needed.
Korean rules for fiscal years starting in 2026; national tax only
Automatic calculations cover ordinary domestic companies with fiscal years starting on the first day of a month in 2026.
An advance-payment cash difference is not an annual tax saving.
The final annual corporate tax is settled separately using the full fiscal year’s income and eligible credits.
All monetary amounts are KRW, and this page does not apply the corporate tax system of another country.
Connect each input with its filing documents
Previous finalized return
Enter prior assessed tax and penalties separately, then verify prior credits/reductions, withholding and occasional assessments.
Exclude the tax on land-transfer income and the investment, dividend and cooperation special tax from the assessed-tax input.
Count previous fiscal-year months using the calendar, with a remaining fraction of a month treated as one month.
Tax-adjusted interim accounts
Use the tax base for the first six months after adjusting taxable income and deductible expenses and lawfully applying loss carryforwards, non-taxable income and income deductions.
Revenue or unadjusted accounting profit can produce a different result.
Enter only credits and reductions actually eligible after the minimum-tax and application requirements have been checked.
The exemption test uses previous-year SME status; the installment period uses current-year SME status.
The business-group revenue-size exception has its own statutory conditions and is not inferred merely from current SME status.
Available cash means money the company can actually use at the first deadline; personal funds of an owner are not automatically assumed to be available.
Use integer won amounts; only a loss in the tax-base field can be entered as a negative amount.
The below-KRW-500,000 exemption differs from a zero payment
- An ordinary domestic company with a fiscal year of six months or less has no interim-tax obligation.
- The first fiscal year of an ordinarily newly incorporated company is excluded; companies formed through mergers or divisions require separate treatment.
- A company that was an SME in the previous fiscal year is exempt if the prior-year formula produces less than KRW 500,000.
Exactly KRW 500,000 does not meet this small-amount exemption.
- The non-collection rule for no revenue during the interim period requires the competent tax office to confirm the relevant suspension or other circumstances.
A low sales figure or accounting loss alone does not establish this fact.
For example, prior assessed tax of KRW 999,998, no deductions and a 12-month previous fiscal year gives an unrounded formula result of KRW 499,999.
With confirmed previous-year SME status, that is an exemption candidate.
Prior assessed tax of KRW 1,000,000 gives KRW 500,000, so the small-amount exemption does not apply.
The threshold comparison uses the formula before discarding payment remainders below KRW 10.
If an interim tax loss produces a zero payment candidate, filing and supporting documents still require review separately from exemption eligibility.
How the prior-year method works
Prior candidate = max(0, assessed tax + penalties − credits/reductions − withholding − occasional assessments) × 6 ÷ previous fiscal-year months
The inputs separate the adjustment terms in Corporate Tax Act Article 63-2(1)(1).
For a 12-month fiscal year, the adjusted tax is halved; for a previous six-month fiscal year, the same adjusted amount is used in full.
Do not subtract prior interim payments or the final self-assessed payment again.
Entering a final net payment as assessed tax and entering its deductions separately counts those deductions twice.
The worked example uses previous assessed tax of KRW 60,000,000, penalties of zero, credits/reductions of KRW 5,000,000, withholding of KRW 1,000,000 and no occasional assessment.
Adjusted tax of KRW 54,000,000 multiplied by 6 ÷ 12 gives a prior-year candidate of KRW 27,000,000.
Payment remainders below KRW 10 are discarded.
The test for whether prior assessed tax exists excludes penalties.
A company with penalties alone is not automatically treated as eligible to choose the prior-year method.
Annualize interim accounts before six-month proration
- Multiply the tax-adjusted base for the first six months by two to obtain the annualized tax base.
- Apply the ordinary Korean 2026 progressive corporate tax brackets to that annualized base.
- Multiply annual assessed tax by 6 ÷ 12, then subtract interim credits/reductions, withholding and occasional assessments.
- Show a negative payment as zero and discard payment remainders below KRW 10.
Refunds of excess withholding and credit carryovers require separate review.
Ordinary Korean corporate tax rates for fiscal years starting in 2026, applied to the annualized base| Annualized tax-base bracket | Marginal rate | Progressive calculation |
|---|
| Up to KRW 200 million | 10% | Base × 10% |
| Above KRW 200 million to KRW 20 billion | 20% | KRW 20 million + excess × 20% |
| Above KRW 20 billion to KRW 300 billion | 22% | KRW 3.98 billion + excess × 22% |
| Above KRW 300 billion | 25% | KRW 65.58 billion + excess × 25% |
An interim base of KRW 40,000,000 annualizes to KRW 80,000,000; annual assessed tax of KRW 8,000,000 prorates to KRW 4,000,000.
Subtract interim credits/reductions of KRW 500,000 and withholding of KRW 100,000 to obtain KRW 3,400,000.
Deducting these amounts before halving the tax produces a different result, so preserve the sequence.
The ordinary rate table does not cover companies under Corporate Tax Act Article 60-2(1)(1), such as qualifying small closely held rental-focused companies subject to special rates.
When the smaller prior-year amount is unavailable
- If there is no finalized previous assessed tax, the interim accounts method is generally required.
This assessment excludes penalties and differs from having assessed tax reduced to a zero final payment by credits or withholding.
- The interim accounts method also applies when the previous corporate tax has not been finalized by the end of the interim period.
- A company belonging to a public-disclosure business group at the previous fiscal year end must use interim accounts unless it satisfies the sector/revenue-size exception.
Separately verify the condition in Restriction of Special Taxation Act Enforcement Decree Article 2(1)(1), referenced by Corporate Tax Act Enforcement Decree Article 100(4).
A confirmed exemption is applied first.
For a confirmed mandatory interim-accounts case, the calculator does not recommend the prior-year amount even when that amount is smaller.
Unconfirmed group membership, size-exception eligibility or the previous SME status needed for a small-amount exemption leaves the figures as references and withholds both method choice and cash-shortfall conclusions.
Statutory treatment of an unpaid interim obligation after the deadline is separate; do not use a small candidate amount to postpone filing.
A practical sequence for using the calculator
- Confirm fiscal year and scope.
Select the start date and current/previous month counts, then verify ordinary domestic-company rates, standalone filing and the absence of merger, division or fiscal-year changes.
- Review exemption and method obligations.
Check incorporation or suspension circumstances, previous SME status, assessment finalization, business-group membership and the separate size exception.
- Enter figures from supporting records.
Separate assessed tax, penalties, credits, withholding and occasional assessments, and enter the interim tax-adjusted base and eligible credits.
- Complete the tax-adjustment confirmation.
Check minimum tax, loss carryforward and credit limits before confirming the checkbox that enables a method candidate.
- Compare available cash with the payment notice.
Review cash at the first deadline, the maximum-deferral assumption and actual approved deadlines; save the TXT review sheet.
Initial amounts are illustrative and the company-scope and tax-adjustment confirmations are not completed.
Load the worked example to display the calculated result under explicitly hypothetical confirmed conditions.
When replacing the example with actual records, verify every condition instead of carrying over the example’s confirmation status automatically.
Examples: weaker earnings, a loss and installments
Hypothetical prior-year and interim accounts candidates with method interpretation| Example | Prior candidate | Interim candidate | Interpretation |
|---|
| Base example; interim base KRW 40 million | KRW 27,000,000 | KRW 3,400,000 | Interim; cash difference KRW 23,600,000 |
| Loss of KRW 20 million; no interim deductions | KRW 27,000,000 | KRW 0 | Review interim filing |
| Interim base KRW 200 million; base deductions | KRW 27,000,000 | KRW 29,400,000 | Prior method; consider installments |
Under verified conditions allowing both methods, the base example selects an interim candidate of KRW 3,400,000.
Available cash of KRW 10,000,000 gives a calculated initial shortfall of zero.
In the third example, a half-year tax base of KRW 200,000,000 makes the prior-year candidate of KRW 27,000,000 smaller.
Maximum deferral of KRW 13,500,000 leaves a first payment of KRW 13,500,000.
The same available cash leaves a KRW 3,500,000 shortage, so review supplier payments and payroll together with the tax schedule.
If mandatory business-group rules apply, the lower prior-year figure is unavailable even in that third example.
Filing deadlines and installments above KRW 10 million
Standard statutory schedule
File and pay within two months after the first six-month period.
For a fiscal year beginning 2026-01-01, the period ends 2026-06-30 and the standard filing/payment deadline is 2026-08-31.
For a 2026-07-01 start, the base date 2027-02-28 is Sunday and the following March 1 is a holiday, so the standard deadline becomes 2027-03-02.
Maximum deferral and initial cash
The payable tax must exceed KRW 10,000,000 for installments.
At up to KRW 20,000,000, the excess above KRW 10,000,000 can be deferred; above KRW 20,000,000, no more than 50% can be deferred.
The period is one month after the normal deadline for ordinary companies or two months for SMEs, with weekend/holiday deadlines moved to the next eligible day.
Exactly KRW 10,000,000 is not installment-eligible; KRW 10,000,010 allows maximum deferral of KRW 10.
An SME with a normal deadline of 2026-08-31 has a two-month date of October 31, which is Saturday, so its standard installment deadline is 2026-11-02.
The ordinary-company installment deadline is 2026-09-30.
NTS relief for specified affected businesses, individual approvals and temporary holidays require checking the actual payment notice.
Selecting extension/special treatment withholds actual payment and installment dates while retaining the standard filing reference.
Do not interpret a payment extension as a filing extension.
Planning scenarios and limitations
Working capital after a sales decline
Prepare tax-adjustment records for inventory, receivables, accrued items, depreciation and other relevant entries first.
A smaller interim amount represents a difference in advance-payment timing; do not treat it as confirmed company profit.
Professional fees and staff time for producing interim accounts are outside the tax comparison and should be assessed using the actual engagement quote.
Losses and tax reductions
A current loss is different from the prior-year SME small-amount exemption.
When withholding exceeds assessed tax, this calculator does not automatically determine an immediate refund.
Using nominal reductions before minimum-tax review can make the interim candidate too low, so verify the amount actually eligible.
Consolidated taxation, mergers/divisions, fiscal-year changes, liquidation, foreign companies, nonprofit exceptions and special rates require individual review.
Fiscal years beginning in 2025 and ending in 2026, and fiscal years beginning in 2027, are outside the automatic scope.
Do not add a flat 10% local corporate income tax to this national interim amount.
The input ceiling of KRW 100 trillion is an implementation limit for numeric stability, not a statutory tax ceiling.
The TXT sheet saves assumptions and unresolved conditions together with figures; distinguish it from an actual return.
Frequently asked questions
Can I always choose the smaller method?
Compare the lower candidate only after ordinary method eligibility, exemption circumstances and tax adjustments are verified.
Business-group requirements, no prior assessed tax or an unfinalized previous assessment may require interim accounts.
Is every interim amount below KRW 500,000 exempt?
The small-amount exemption depends on previous-year SME status and a prior-year formula result below KRW 500,000.
A small interim-accounts candidate alone does not establish exemption.
Exactly KRW 500,000 is outside this exemption.
Does a previous zero final payment require interim accounts?
Check whether finalized assessed tax existed excluding penalties.
Having assessed tax reduced to a zero payment by credits or withholding differs from having no assessed tax.
Can I choose no-revenue exemption immediately when sales are zero?
The competent tax office must confirm the relevant no-revenue circumstances during the interim period.
A loss or low sales alone is insufficient; compare actual exemption or non-collection treatment with the office.
Can I enter accounting net income?
Enter the tax-adjusted base after lawfully applying loss carryforwards, non-taxable income and income deductions.
Accounting profit may still need tax adjustments, so review the documents before completing the confirmation.
Should I also deduct previous interim tax payments?
The prior formula deducts credits/reductions, withholding and occasional assessments from finalized assessed tax.
Subtracting previous interim or final self-assessed payments again can double-count taxes already reflected.
Do installments reduce total corporate tax?
Installments defer part of the same payment within the statutory limits.
The calculator shows the minimum first payment under maximum deferral and keeps total candidate tax unchanged.
Verify the actual installment filing and payment notice.
Does relief move the August 31 filing deadline too?
Payment extensions and filing extensions are separate.
The NTS 2026 guidance includes relief that extends payment while retaining the normal filing deadline, so check the Hometax approval directly.
Official sources, effective dates and next actions
Official sources were checked on October 7, 2026.
The National Law Information OPEN API was directly queried for Corporate Tax Act MST 280349, its Enforcement Decree MST 290843, Framework Act on National Taxes MST 289999 and National Treasury Funds Management Act MST 276079.
Corporate Tax Act Articles 55, 63, 63-2 and 64 govern the rates, obligations, calculation and installments; Enforcement Decree Articles 100 and 101 govern the documents, group-size exception and deferral amounts.
Framework Act on National Taxes Article 5 supplies the deadline rollover, and National Treasury Funds Management Act Article 47 supplies whole-won tax bases and payment rounding below KRW 10.
Act No. 21217 Addenda Articles 1 and 5 make the ordinary 10%, 20%, 22% and 25% rates applicable to fiscal years beginning on or after 2026-01-01.
Distinguish the current Corporate Tax Act version’s overall effective date of 2026-07-01 from the relevant rate/interim provisions effective 2026-01-01.
The current Enforcement Decree version is effective 2026-10-01 and the Framework Act version 2026-10-02.
The NTS interim guidance dated August 4, 2026 confirms the calendar-year standard schedule; KASI calendar sources inform the related 2026 and 2027 holiday dates.
Temporary holidays, later legal amendments and approved company-specific payment dates still require rechecking.
The linked revenue-size condition was also checked in Restriction of Special Taxation Act Enforcement Decree Article 2(1)(1), current MST 288915 effective 2026-09-18.
The company must separately verify whether its actual sector and revenue satisfy that condition before confirming the exception input.
Review the comparison with the half-year documents
Prepare the previous return and interim tax-adjustment records, then save the candidates, exemption status and installment budget as TXT.
Confirm the actual method, minimum tax and payment notice in Hometax or with a Korean tax professional before finalizing the payment plan.
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