On 1 January 2027 at midnight, Korea decides what your crypto cost you.
The tax takes effect, and for every asset you already hold the statute replaces your acquisition cost with the greater of what you actually paid and the market price at the cut-over. Read once, that sounds like a gift. Read twice: the snapshot is a floor, so it only ever helps — and the difference between it and what you really paid is yours only if you can prove the real figure. This page works out whether that is worth anything to you, asset by asset, and tells you when it is not.
The reference instant is 2027-01-01 00:00 KST — set by 소득세법 시행령 제88조제2항, which measures the posted price at midnight, averaged across the operators the NTS designates. Not the close of 31 December.
The rule, in the statute's own words
제1항제3호의 필요경비를 계산할 때 2027년 1월 1일 전에 이미 보유하고 있던 가상자산의 취득가액은 2026년 12월 31일 당시의 시가와 그 가상자산의 취득가액 중에서 큰 금액으로 한다.
In calculating necessary expenses, the acquisition cost of virtual assets already held before 1 January 2027 is the greater of the market price as at 31 December 2026 and the acquisition cost of that virtual asset. — 소득세법 제37조제5항
Up on the position
Paid 10 million won, worth 60 million at the cut-over. The snapshot is the greater figure, so your basis is 60 million whether you kept a single receipt or none. Records change nothing. We will say so rather than sell you a reconstruction you do not need.
Down on the position
Paid 100 million, worth 60 million at the cut-over. Prove the 100 and it is your basis; a later sale at 70 million is a 30 million loss. Fail to prove it and your basis is the 60 million snapshot, and that same sale is taxed on a 10 million gain you never made.
Nothing quotes it
Delisted, DEX-only or sitting in your own wallet. The decree sources the snapshot from prices posted at an operator; where none exists there is no figure under either limb, and the 50% rule does not reach pre-2027 holdings. Documented cost is the only route to a basis at all.
What is it worth to you?
One row per asset you held at the cut-over. Everything stays in this browser. Leave the cost blank for anything you genuinely cannot document — that is the case the calculator is for.
Nothing you entered left your browser. Won figures are whole won, as the statute computes them. Information, not advice — and the designation of which exchanges supply the 00:00 price for income-tax purposes has not been published yet, so treat your snapshot figure as your own estimate.
What happens after the snapshot
The charge
20% national plus 2% local — 22% combined — on the year's net gain after a 2,500,000 won deduction. That figure is also a floor: at or under it, no income tax arises at all. The two rates are computed independently on the same base in two different statutes, so it is not a 10% surtax on the national tax.
How it is taxed
As separately-taxed other income. It never joins your global income and never meets the 6–45% ladder — and it is not capital gains, so there is no holding-period relief and, as the statute stands, no loss carry-forward. Losses within a single year do net against gains.
Which lots are sold
Total average, per resident per asset, since the decree was amended in February 2025. This replaced per-wallet moving-average and FIFO — guidance still describing 이동평균법 predates the change, and the transition basis enters as the opening layer of each asset's pool.
When you file
Self-assessed, in the ordinary 1–31 May window of the following year. The first return is May 2028 for the 2027 year. No withholding for residents — a non-resident is a wholly different regime, where withdrawing from a Korean operator is itself a disposal.
Questions people actually ask
What exactly happens on 1 January 2027?
Nothing you have to do, and everything to your numbers. Korea's income tax on virtual assets takes effect, and for anything you already held the statute fixes your acquisition cost at the greater of what you actually paid and the market price at the cut-over. The decree measures that price at 00:00 on 1 January 2027, averaged across the exchanges the National Tax Service designates — not at the close of 31 December, which is the figure most people will reach for.
If I have no records, do I get a zero cost?
No. This is the most common misconception and it is worth being clear about: the greater-of formula resolves to the snapshot, and the snapshot becomes your basis. You are never pushed to zero. What you forfeit is only the amount by which your real cost exceeded the snapshot — which is nothing at all if you are up on the position.
So when do records actually matter?
Only where you paid more than the coin is worth at the cut-over. Bought at 100 million won and worth 60 million on Basis Day: prove the 100 and your basis is 100, sell later at 70 and you have a loss. Fail to prove it and your basis is the 60, and that same sale is taxed on a 10 million gain you never made. Bought at 10 million and worth 60: the snapshot is higher, it carries you, and you can stop reading.
What about a coin that is delisted, DEX-only or in my own wallet?
That is the genuine gap in the statute, and it points the other way. The decree sources the snapshot from prices posted at an operator; where nothing quotes the asset there is no figure under either limb. The 50% deemed-cost rule does not reach anything acquired before 2027. For those assets documented cost is not the better answer — it is the only one, which makes them the first thing to reconstruct.
Does the 50% rule save me?
Only from 2027 onward. It is a separate provision, it applies to assets acquired on or after 1 January 2027 where you bought outside an exchange and cannot substantiate the cost, it is fixed at exactly 50% of the total disposal value for that whole asset, and it forfeits your fees. Korean commentary regularly presents it as part of the transition rule. It is not.
Is the 2027 start actually final?
It is what the statute says, set by the amendment of 31 December 2024, and the government's tax reform package of 3 August 2026 did not defer it again. A bill to abolish the tax outright went to subcommittee in July 2026, so a fourth deferral is legislatively possible until the end of the year. We report the law as it stands rather than predicting the National Assembly — and note that if it is deferred again, nothing you did to document your acquisition costs is wasted.
If the answer above was "yes, it is worth something", the work starts now.
Documenting an acquisition cost gets harder every month — exchange export windows close, platforms shut, and the wallet you used once in 2021 is still yours to account for. Rebuild the chain from your own transaction history for free and see what is provable before the snapshot is taken, not after.
Rebuild my acquisition history — free The full Korea guide →
Sources, retrieved 28 August 2026: 소득세법 제37조제5항 and 제37조제6항 (transition basis and the 50% rule) · 제21조제1항제27호 and 제14조제3항제8호다목 (classification) · 제64조의3제2항 and 제84조제3호 (rate, deduction, de-minimis floor) · 지방세법 제93조제18항 (local 2%) · 소득세법 시행령 제88조 (snapshot price source, the 00:00 reference instant, total-average method, the 50% ratio) · 제70조제2항 (filing window) · 국세청 — 거주자의 가상자산소득 과세 개요. The NTS notice designating which operators supply the 00:00 price for income-tax purposes has not been published; the existing notice names five exchanges for inheritance and gift valuation, which is a different measurement. ClearBasis is tax software, not a tax adviser, and this is information rather than advice.