I'm a Korean resident who's been holding crypto across Binance, Bybit and OKX for a few years. This is my second time filing the NTS overseas financial account report and I keep seeing fellow Koreans on this sub miss the rule, so I figured I'd write up what I learned. Sources at the bottom — I'm not a tax professional, just a guy who got tired of guessing.

TL;DR

• Who: Korean tax residents (and Korean nationals not falling under the expat exemptions) who held overseas financial accounts — including overseas crypto exchange accounts — exceeding KRW 500M (~$370k) at any point.
• Threshold: combined balance exceeded KRW 500M on any single month-end during 2025 (Jan 31, Feb 28, Mar 31 … Dec 31 — twelve snapshots).
• Deadline: June 1 – June 30, 2026 for the 2025 reporting year.
• Form: Schedule No. 45 (별지 제45호) "해외금융계좌 신고서", filed via Hometax (hometax.go.kr) or Sontax mobile.
• Penalty: 10% of the unreported amount, capped at KRW 1 billion (higher rate of 20% for fraudulent filing or failure to justify the source of funds). Voluntary late filing before NTS notifies you can reduce the penalty by up to 90%.
• Source: nts.go.kr official guide.

What counts

• In scope: Binance, Bybit, OKX, KuCoin, Gate.io, MEXC etc. — exchanges with their head office abroad. Custodial wallets where an overseas service holds your keys.
• In scope (yes, this surprises people): USDT, USDC and any stablecoins. They're crypto assets under Korean law; you don't get to exclude them because they're "stable".
• In scope (also surprising): residual claims on bankrupt or shut-down exchanges (FTX-style claims). You report them at a price quoted on a domestic or overseas exchange where the asset still trades.
• Out of scope: Upbit, Bithumb, Coinone, Korbit (domestic VASPs).
• Out of scope under the current interpretation: non-custodial wallets where you hold the keys yourself (MetaMask, Ledger, Trezor and similar cold wallets). NTS doesn't currently treat these as "accounts." Worth re-checking each year because the interpretation could change.

Common misconceptions I had myself

1. "I'm under 500M on June 30 so I'm fine." Wrong. The rule looks at every month-end during the reporting year. If your combined balance exceeded 500M on, say, January 31 and you cashed out by June, you still file.
2. "Binance doesn't report to Korea." They don't directly, but Korea participates in CRS and similar information-exchange frameworks. NTS gets data from foreign tax authorities and uses it to find non-filers. The penalty assessment statute of limitations is 5 years.
3. "USDT is just dollars." Legally it's a virtual asset. Include it.
4. "I missed the deadline so I'm screwed." Late filing is allowed, and voluntary late filing before NTS hits you with a notice can knock the penalty down by up to 90%.
5. "My cold wallet pushes me over 500M, I have to report it." Under the current interpretation, no. Custodial overseas exchanges and overseas custodial wallets count; self-custody does not.

Valuation rules (the painful part)

You need the last price on the last day of each month for each asset, sourced from the exchange you actually held it on. Then convert to KRW using the per-day base rate or arbitraged rate under the Foreign Exchange Transactions Act. You sum across exchanges per month-end.

If you held it on a defunct exchange, you can pick a month-end last price from a domestic or overseas exchange where the asset still trades.

This is where most people (myself included) lose a weekend. Twelve month-ends × N exchanges × M tokens × FX conversion is genuinely tedious. Some exchange APIs make month-end snapshots a pain to extract; you'll often see daily trade history instead of clean balance snapshots.