Korea's Securities Transaction Tax Explained: Why You Pay Even on a Losing Trade

You Sold at a Loss, and Money Still Came Out

Imagine buying a KOSDAQ stock for 20 million won and selling it for 18 million won — a clean 2 million won loss. No profit, so no tax, right? Check the brokerage app right after the sale settles, though, and a small tax charge has already been deducted from the full 18 million won proceeds. Losing money and still paying tax on the trade feels like a contradiction. It isn't one — it's the defining feature of Korea's securities transaction tax, a tax that, unlike the capital gains tax on stocks, was never designed to ask whether you made money in the first place. This lesson walks through exactly what the tax applies to, why the rate differs between KOSPI and KOSDAQ, and why it went up again in 2026 after years of being cut.

A Different Tax Base Entirely: Transactions, Not Profit

The securities transaction tax is levied every time ownership of a listed share changes hands through a sale — it taxes the transaction itself, not the gain from it. The formula is deliberately simple:

Transaction tax = sale proceeds × tax rate

Nowhere in that formula does the purchase price appear. Whether the trade made money or lost money is irrelevant to the calculation. This is a fundamentally different design philosophy from an income-based capital gains tax: it functions more like a stamp duty or a transfer tax on real estate than like an earnings-based levy. For the large majority of retail investors who fall below Korea's "major shareholder" thresholds and therefore owe no capital gains tax on domestic stock trades at all, this transaction tax ends up being effectively the only tax connected to their day-to-day buying and selling. One more detail worth keeping in mind: it applies only when you sell, never when you buy.

Why KOSPI and KOSDAQ Rates Differ: A Tax Riding on Another Tax

Look closely at a trade confirmation and the rate applied to a KOSPI stock sale differs from the rate applied to a KOSDAQ sale, even though both are described as the same "securities transaction tax." The reason traces back to a second, unrelated-sounding tax layered on top: the Special Tax for Rural Development.

That surtax was introduced in 1994 to fund adjustments for Korean agriculture as the Uruguay Round trade agreement opened domestic farm markets to import competition. It was designed to piggyback on a range of other taxes — customs duty reductions, acquisition tax, and, as it happened, share transfers on the KOSPI exchange. KOSDAQ and KONEX trades were never brought into its scope. That one historical decision means that decades later, whenever the government cut the base securities transaction tax rate, KOSPI investors kept paying the 0.15% rural-development surtax regardless, while KOSDAQ investors paid none of it but carried a relatively higher base transaction tax rate instead.

In practice, when officials announced "transaction tax cuts" over the past several years, they mostly meant cuts to KOSPI's base rate. By 2023–2025, that base rate had fallen essentially to zero, leaving only the 0.15% rural-development surtax as KOSPI's effective cost. KOSDAQ, over the same stretch, carried a 0.15% base rate with no surtax attached. The two headline numbers looked identical, but they were built from entirely different components.

How the Rate Got Here — and Why It Reversed

The rate has never been a fixed constant; it has moved with policy cycles for decades. As recently as the mid-1990s the effective rate ran as high as 0.5%, then trended steadily lower for years under the banner of stimulating market activity. The most consequential recent chapter was tied directly to a different tax altogether: the Financial Investment Income Tax, originally scheduled to take effect in 2023, which would have taxed realized trading gains directly. Lawmakers reasoned that once gains were taxed that way, continuing to also tax every transaction regardless of profit would amount to double taxation — so they agreed to phase the transaction tax down toward roughly zero on KOSPI and 0.15% on KOSDAQ as that new capital-gains tax came online.

The capital-gains tax, however, was delayed twice and then scrapped outright by the National Assembly at the end of 2024. That left the transaction-tax cuts that had been paired with it in an awkward position — cuts made in anticipation of a tax that was never actually going to arrive. The government's answer was to partially reverse them for revenue: starting in 2026, KOSPI's base rate rose from 0% to 0.05%, bringing its effective rate (with the surtax) to 0.20%. KOSDAQ and K-OTC rose from 0.15% to 0.20%, and KONEX settled at 0.10%. Officials project the increase will raise roughly 11.5 trillion won in additional revenue between 2026 and 2030. None of this should be read as permanent — every time KOSPI trades near record highs, the political debate over reviving a capital-gains-based system resurfaces, and the transaction tax rate could move again.

Running the Numbers: Why Losses Don't Exempt You

Take Investor A, who buys a KOSDAQ stock for 20 million won and sells it for 18 million won — a 2 million won loss. At the 2026 KOSDAQ rate of 0.20%:

• Sale proceeds: 18,000,000 won
• Transaction tax: 18,000,000 × 0.20% = 36,000 won

A loses 2 million won on the trade and pays an additional 36,000 won in tax on top of it. Now take Investor B, who buys the same stock for 20 million won and sells it for 22 million won, a 2 million won gain:

• Sale proceeds: 22,000,000 won
• Transaction tax: 22,000,000 × 0.20% = 44,000 won

It's tempting to read B's tax as "tax on the 2 million won gain," but it isn't — it's 0.20% of the full 22 million won sale price. Had B sold at exactly the 20 million won break-even point, the tax bill would still have been 40,000 won. This mechanic matters most for frequent trading: an investor with 100 million won in cumulative annual sales pays roughly 200,000 won in transaction tax over the year on KOSDAQ, or the same on KOSPI, regardless of whether the year nets out positive or negative. Stack that on top of brokerage commissions across many trades, and the transaction tax becomes a real structural drag that makes frequent buying and selling harder to break even on, independent of how good any individual pick turns out to be.

Why ETFs Are Exempt

One thing investors often miss: domestically listed ETFs carry no securities transaction tax at all. The reason is legal classification, not a special carve-out for ETFs specifically. The Securities Transaction Tax Act applies only to the transfer of "shares" (jukwon), and an ETF is legally structured as a trust's beneficiary certificate, not a share — so it simply falls outside what the law taxes in the first place. That's a genuine cost advantage ETFs hold over individual stocks. It doesn't mean ETFs are untaxed altogether, though: domestic equity ETFs are tax-free on trading gains just like individual domestic stocks, while domestically listed ETFs tracking foreign indices have their trading gains classified as dividend income and withheld at 15.4%, and ETF distributions are taxable regardless of type. The absence of transaction tax and the taxation of trading gains are two separate questions.

A Double-Edged Policy Lever

Transaction tax changes ripple beyond government revenue. Because the cost compounds with every sale and every trading cycle, researchers and regulators have long tracked how rate cuts and hikes correlate with shifts in daily trading volume and turnover — average daily trading value has tended to tick up, at least temporarily, following past rate cuts. That makes the transaction tax a genuinely two-sided policy tool: a lever to stimulate liquidity when lowered, and a friction device to discourage excessive short-term or high-frequency churn when raised.

Korea is far from alone in using a tax like this. The UK charges a 0.5% Stamp Duty on share purchases; Hong Kong, Taiwan, and Singapore each run their own versions of a transaction or stamp tax. The US, by contrast, has no financial transaction tax at all and relies entirely on capital-gains taxation of realized profits. Korea's long back-and-forth between a transaction tax and a capital-gains tax isn't really a binary choice — it reflects a spectrum that major exchanges around the world sit on in different proportions.

How It Stacks With Capital Gains Tax

The transaction tax and capital gains tax aren't mutually exclusive — they can both apply to the same sale. Most retail investors pay only the transaction tax, but anyone who crosses Korea's major-shareholder thresholds (by ownership percentage or holding value in a given stock) owes capital gains tax on top of it, not instead of it. A major shareholder selling 200 million won of a KOSPI stock, for example, first pays 400,000 won in transaction tax (200 million × 0.20%) and separately settles capital gains tax of 20–25% (22–27.5% including local tax) on the actual profit from the sale. The two taxes differ in what they tax (transaction amount vs. profit) and when they're collected (withheld immediately at sale vs. self-filed the following May) — paying one never substitutes for the other.

Key Takeaways

• Korea's securities transaction tax is charged on the sale amount itself, not on profit, so it applies even to trades that lose money.
• KOSPI's effective rate combines a base transaction tax with the rural-development surtax, while KOSDAQ and KONEX carry no surtax and rely solely on the base rate — the two markets' effective rates are built differently even when the headline numbers look similar.
• From 2026, KOSPI's effective rate is 0.20% (0.05% base + 0.15% surtax), KOSDAQ and K-OTC are 0.20%, and KONEX is 0.10%, reversing part of the cuts made when a capital-gains tax was expected to replace them.
• Domestically listed ETFs are exempt from the transaction tax because they're legally classified as trust units rather than shares, though trading-gain taxation still varies by ETF type.
• Major shareholders owe both the transaction tax and capital gains tax on the same sale, since the two are assessed on different bases and collected differently.
• Rates have changed repeatedly with each policy cycle, so anyone calculating real trading costs should check the current published rate rather than assume it's fixed.

FAQ

Do I really pay tax on a trade that lost money?

Yes. The tax is calculated on the sale amount, not on the gain, so it is withheld automatically the moment a sell order settles — regardless of whether that trade was profitable. This is the single biggest difference from capital gains tax, which only applies when there's an actual profit.

Does this tax apply when I trade US or other foreign stocks?

No. Korea's securities transaction tax applies only to shares traded on Korean exchanges (KOSPI, KOSDAQ, KONEX). Trades executed on foreign exchanges are subject to whatever fees or taxes that jurisdiction imposes instead — for example, a small SEC transaction fee in the US — not Korea's securities transaction tax.

Is the tax charged when I buy shares too?

No. It's charged only at the point of sale. A full buy-and-sell round trip is taxed once, on the sale leg only.

⚠️ This article is for educational purposes only and is not tax or investment advice. Securities transaction tax rates and related rules change with each year's tax legislation, so verify the current rate with the National Tax Service, the Korea Exchange, or a qualified tax professional before relying on it for actual trading or filing decisions.