The regular EITC calculator noted that it "works on the regular May claim and does not cover the half-year route". This article opens that route. What stands out is not the 35 per cent advance everyone quotes - it is the "months worked" inside the annualising formula. The fewer months you worked, the larger your income is deemed to be.
1. First-half income is annualised. The statutory formula is (wage income ÷ months worked) × (months worked + 6) - a multiplier of seven times at one month, twice at six.
2. Only 35 per cent arrives early. The rest waits for the settlement.
3. Two cases pay nothing in September. Where the first-half amount is under 150,000 won, or where it already reaches the full-year figure so a clawback is expected - neither is a loss, both are settled later.
It follows arts. 100-5(2), 100-6(7) and 100-8 of the Restriction of Special Taxation Act as written. A half-year claim is open only where you and your spouse had wage income alone during that half (Decree art. 100-7(9)), and is filed 1-15 September for the first half and 1-15 March of the following year for the second. The first-half amount takes the statutory formula (wage income ÷ months worked) × (months worked + 6), treats that annualised figure as the total wage for the period, works out the credit on it, and pays 35 hundredths of the result. Months worked counts only months of 15 days or more and applies to those still in regular employment on 30 June; for day labour and the pay of someone who left mid-year it is six months regardless (Decree art. 100-6(3)). Assets of 170m won or more halve the amount again (art. 100-5(4)). Two cases pay nothing in September - where the first-half amount is under 150,000 won (Decree art. 100-9(4)), or where it already reaches the full-year figure, so "a clawback is expected" (same art., para. 5). Neither is a loss: both are cleared in the settlement by 30 June the following year (art. 100-8(8)). This calculator does not rebuild the credit table - take the two table amounts from the regular calculator and enter them. How far the "notwithstanding" in art. 100-5(5) reaches is not settled by the text alone, so the order used here is: annualise, then the table, then 35 per cent, then the asset halving. An estimate - the actual amount is fixed by the tax office (helpline 126).
Annualising - fewer months, bigger figure
Art. 100-5(2)1 sets the first-half credit as "35 hundredths of the amount worked out under paragraph 1, treating the figure produced by the following formula as the total wage for that period". The formula is (A ÷ B) × C, where A is first-half wage income, B is months worked and C is months worked + 6.
Because the multiplier is (months + 6) ÷ months, it grows as the months shrink. One month counted gives seven times, two gives four, six gives twice.
Months worked is defined by Decree art. 100-6(3): a month counts only where 15 days or more were worked, and the rule applies to those still in regular employment on 30 June of the claim year.
The proviso in the same paragraph reverses the direction. "For day-labour income, and for the regular pay of someone who left mid-year, months worked shall be taken as six months regardless of the actual number." Work one month and leave, and the multiplier is still fixed at twice. It moves only for those who stay.
Only 35 per cent comes early
The first-half payment is 35 hundredths of the credit worked out on the annualised figure. A table amount of 1m won gives 350,000 won; 1.65m gives 577,500 won.
The second half is defined by subparagraph 2 as "the amount worked out under paragraph 1 less the first-half credit already refunded" - the full-year figure minus whatever has already arrived.
Assets cut it again. Art. 100-5(4) halves the credit where total assets reach 170m won, and it says "the amount worked out under paragraphs 1 and 2" - so the half-year figure is caught too.
The two cases that pay nothing in September
Art. 100-8(5) names two situations where a valid claim is not refunded at the time.
- Too small. The first-half amount is under "the amount prescribed by Presidential Decree" - Decree art. 100-9(4) puts that at 150,000 won.
- Too big. "A clawback is expected" - and the formula in para. 5 of the same article reads first-half amount ≥ the full-year figure. The advance has already used up the whole year.
Neither is a loss. Art. 100-8(8) requires the office to compare what was already refunded against the full-year figure by 30 June of the following year and refund or claw back the difference.
Half-year claims are also decided and paid faster: art. 100-8(3) gives 30 days from the decision for a regular claim and 15 days for a half-year one.
Two windows, a fortnight each
Art. 100-6(7) fixes the dates: first-half income from 1 to 15 September, second-half income from 1 to 15 March the following year. Nothing to do with the regular May window.
Paragraph 9 adds that claiming the first half is taken, "according to the claimant's intention", as claiming the second too. File once in September and March follows automatically.
Eligibility comes from Decree art. 100-7(9): you and your spouse must have had wage income only during that half. Business or religious income puts you back on the regular route.
And if you have other income but file a half-year claim anyway? Art. 100-6(3) provides that you are "deemed to have made the claim under paragraph 1" - the regular claim, not the half-year one. In that case the settlement deadline is 30 September, not 30 June (proviso to art. 100-8(8)).
How an overpayment comes back
Where the settlement produces a clawback, Decree art. 100-9(7) sets the order: first from that tax period's child credit; then, if anything remains, from the work and child credits of the next ten tax periods; and any remainder is billed as income tax. On request the claimant can be billed at once instead.
Up to 2.5m won a year of a refunded credit cannot be seized (Decree art. 100-9(6)), and unpaid national tax is set off against the refund up to 30 per cent of it (art. 100-8(4)).
Questions that remain
Does this calculator build the credit table? No. The table belongs to the regular calculator. This one gives you the annualised figure; put that and the full-year wage total through the regular calculator, and bring the two table amounts back here.
Why the order "annualise, table, 35 per cent, asset halving"? Art. 100-5(5) says the credit is worked out from the table "notwithstanding paragraphs 1, 2 and 4", and how far that "notwithstanding" reaches - whether it swallows the 35 per cent and the asset halving too - is not settled by the text. The reading here is that the table fixes the amount while the half-year rate and the asset cut still apply. That is our choice, stated plainly.
Is the child credit paid half-yearly too? No. As the overview article noted, art. 100-31(1) leaves the half-year provision out of what it borrows. Claiming the work credit half-yearly is, however, taken as claiming the child credit as well.
What about a month with fewer than 15 days worked? It drops out of months worked. So fewer months means a bigger multiplier and a bigger annualised figure - which helps on the rising part of the table and hurts on the falling part.
Sources
Korean Law Information Center, Restriction of Special Taxation Act - the statute - source for art. 100-5(2) (the annualising formula, the 35 per cent, the subtraction for the second half), (4) (170m won of assets, 50 per cent), (5) (the table prevails), art. 100-6(7), (9) and (3) (the September and March fortnights, automatic second-half claim, other income), art. 100-7(1)2 and (3) (the half-year decision deadline and the minimum guarantees) and art. 100-8(3), (4), (5), (8) (15 days to pay, 30 per cent set-off, the two holds, the 30 June settlement).
Enforcement Decree of the same Act - the statute - source for art. 100-6(3) (months worked: 15 days or more, still employed on 30 June, six months for day labour and mid-year leavers), art. 100-7(9) (you and your spouse, wage income only) and art. 100-9(4), (5), (6), (7) (the 150,000 won threshold, the clawback-expected formula, the 2.5m won seizure exemption, the clawback order).
Calculator check. 2,880 combinations were run against the statutory arithmetic in both languages - not only the amounts and labels, but the annualised figure and months worked in the table rows.
Where to check further
The credit table. The bracket amounts in Table 11 have an article of their own - the one about the table always paying slightly more than the formula.
What counts as "still employed on 30 June". Leave of absence and unpaid leave are not addressed in the text - ask the tax helpline (126).
Payment statements. The A in the formula is wage income as filed under Income Tax Act arts. 164 and 164-3 - if the employer files late, it may not reach that half-year claim.
Household type and assets. This calculator covers only the half-year rules; single, single-earner and dual-earner households are dealt with in the household article.
Based on the provisions in force in 2026. The formula, the rates and the fixed sums are as written; the multipliers and worked examples are ours. The calculator is an estimate and the actual amount is fixed by the tax office - confirm on the helpline (126).
