Ex-Dividend Date in Korea: How Late Can You Buy?

To collect a dividend on a Korean stock, your buy order must be executed two business days before the record date. Korean equities settle on T+2, so shares bought today only become legally yours two business days later — and the shareholder register that determines who gets paid is built from settlement, not execution. Buy on the ex-dividend date, which falls one business day before the record date, and you are already too late.

That part is an old rule. What breaks people's math from 2025 onward is something else: record dates no longer sit reliably on 31 December or on quarter-end. A change in the law flipped the old sequence, and some companies now set record dates weeks away from the calendar dates investors were used to counting back from.

Why buying on the ex-dividend date is too late

The record date fixes which shareholders receive the dividend, and your name must appear on the register that day. The ex-dividend date is the business day before it, and KB Think notes that anyone buying from that day forward misses the payout. The reason is the settlement cycle alone: a trade executed on the ex-date settles the business day after the record date, arriving after the register has closed.

The reverse direction is counter-intuitive. Selling on the ex-dividend date does not forfeit the dividend. That sale also settles two business days later, so the seller's name is still on the register as of the record date. The ex-date is the first day you cannot buy in — not a deadline for holding on.

The register records settlement, not execution. The ex-dividend date is the first day you miss out, not the last day you may sell.

The weekday of the record date moves your deadline

The two-business-day rule is fixed, but how many calendar days that means depends on the weekday. Weekends stretch the gap. The table below works backwards from each possible record-date weekday, assuming no public holidays.

If the record date is a Monday or Tuesday, your deadline is the previous Thursday or Friday, not the same week. Add a holiday cluster and the gap widens to six calendar days, as in the final row. Memorising "two days before" in calendar terms is exactly how people miss the window.

Ex-dividend drop versus after-tax dividend

On the ex-dividend date the share price typically adjusts downward, since cash equal to the dividend is leaving the company. The theoretical drop is dividend per share ÷ previous close. What actually lands in your account, however, is the dividend net of 15.4% withholding (14% income tax plus 1.4% local tax). Putting both on the same scale exposes the structure.

The last column follows a rule: the gap in percentage points is always dividend yield × 15.4%. That is why a 5% yield produces 0.77%p and a 7.5% yield produces 1.155%p. If the price falls exactly by the theoretical amount, the tax portion is structurally not recovered — and the higher the yield, the wider that gap grows in proportion.

Real ex-dividend sessions rarely track the theory. Broad market direction, post-payout flows and institutional reinvestment can leave the drop shallower or deeper than calculated. So treat the table as a baseline rather than a forecast: a ruler for judging whether the actual decline was shallow or steep. Rights-adjustment prices are reverse-engineered the same way, as covered in the piece on bonus-issue rights-adjusted pricing.

Record dates may no longer sit at quarter-end

Under the old practice, a company first fixed the shareholders of record as of the end of March, June, September or December, and only then decided how much to pay. Investors had to cross the record date without knowing the amount — a structure the Financial Services Commission attacked directly in its dividend procedure reform plan.

For quarterly dividends, an amendment to the Financial Investment Services and Capital Markets Act reversed the order. As Shin & Kim summarises, the revision that took effect on 21 January 2025 lets the board fix the dividend amount first and then designate a record date within 45 days of that quarter-end. Year-end dividends can be handled the same way at companies that amended their articles of incorporation at the annual general meeting.

Two things change for investors. First, there is now a window to see the amount before deciding to buy. Second, the record date is no longer a calendar constant. Two companies in the same sector can land on 30 June and early August depending on whether they amended their articles. Dividend timing has become something to read off the company's cash-dividend disclosure, not something to infer.

What to watch

• The record date in the disclosure — do not assume quarter-end or year-end; read the date in the cash-dividend resolution filing. Companies that amended their articles have pushed it back.
• Weekday and preceding holidays — work backwards using the table above. A Monday or Tuesday record date, or a holiday cluster, pulls the deadline four to six calendar days earlier.
• Theoretical ex-dividend drop — compute dividend ÷ previous close in advance, then compare the actual decline against it on the day.
• Compare after tax — subtract 15.4% from the headline yield to see what remains. Once financial income grows, the aggregate taxation brackets have to enter the calculation too; the separate-taxation thresholds are laid out in the article on separate taxation of dividend income.
• Articles-of-incorporation history — checking whether a record-date amendment passed at the AGM tells you in advance what shape the next dividend schedule will take.

Sources

• Record date vs ex-dividend date: when to buy — KB Think
• Capital Markets Act amendment on dividend procedures — Shin & Kim
• Dividend procedure reform so investors can see the amount first — Financial Services Commission