Korean brokerage CMA accounts — cash management accounts — fall outside the Depositor Protection Act in every form except the rare jonggeum (merchant-bank) type. Posted retail rates from Korea Investment & Securities run 2.30% annualized for the RP type (days 1–30), 2.60% for the issued-note type (day 1), and 2.58–2.92% for MMF types depending on the fund. The gap between types is roughly 0.3 percentage points, and it is not the product of yield competition — it reflects whose debt your cash turns into the moment it lands. Picking a CMA type is really picking how many days of whose credit risk you are willing to hold.
Where the Money Actually Goes
The same account label hides four different destinations. RP accounts buy repurchase agreements backed by the broker's bond inventory. Issued-note accounts buy notes the brokerage itself has written. MMF accounts buy into an ultra-short bond fund. MMW accounts sit as deposits at the Korea Securities Finance Corporation. Only the issued-note type exposes you directly to the brokerage's own balance sheet — the single largest structural difference. Mirae Asset Securities' issued-note disclosure states in its opening lines that the product is a short-term funding instrument for the issuer and is not covered by the Korea Deposit Insurance Corporation.
| Type | Underlying | Rate basis | Withdrawal | Deposit insurance |
|---|---|---|---|---|
| RP | Repos backed by investment-grade bonds | Fixed | Same day | Not covered |
| Issued note | Notes issued by the brokerage | Fixed | Same day | Not covered |
| MMF | Money market fund, ultra-short bonds | Performance-based | Next day (order by 17:00) | Not covered |
| MMW | Deposits at Korea Securities Finance | Performance-based | Same day | Not covered |
Withdrawal timing bites before the rate does. Only MMF settles next day, so if the account doubles as the source for card bills or stock settlement, a slightly higher headline rate is unusable. RP, issued-note and MMW all clear same day, leaving them on equal footing for parking cash.
The Only Insured Slice Is Uninvested Cash
Korea's deposit insurance ceiling rose to 100 million won — principal plus interest — on 1 September 2025. The Financial Services Commission called it the first increase in 24 years, applied automatically regardless of when an account was opened. The catch is that this ceiling barely touches a CMA.
The Korea Deposit Insurance Corporation covers, at a brokerage, cash left sitting in the account and not deployed into a purchase. Its explicitly excluded list includes investment products such as beneficiary certificates and MMFs, repurchase agreements, and notes issued by large-scale investment banks. Money in a CMA converts into one of those the instant it arrives, so the insured portion is whatever loose change has not yet been deployed. The lone exception is the jonggeum-type CMA offered by firms still holding a merchant-banking licence.
The real distinction is not whether the product is safe but what makes it safe. RP accounts stand on collateral bonds; MMW accounts stand on an institution that buys government and monetary-stabilization paper. Rare losses in practice and a statutory promise to repay 100 million won when an issuer fails are two different kinds of protection.
How Many Days Does That 2.60% Actually Cover?
Reading the posted rate as a plain annual yield produces the wrong number. On Korea Investment & Securities' schedule, the retail RP rate of 2.30% applies from day 1 through day 30; from day 31 it reverts to the prevailing CMA yield. The issued-note rate of 2.60% is narrower still — it applies to day 1 only, with day 2 onward reverting to the prevailing yield. MMF types are performance-based to begin with, so the 2.58–2.92% band is an outcome, not a promise.
Assume the posted rate held for the full period, park 10 million won for 30 days, and net out the 15.4% interest income tax (14% income tax plus 1.4% local surtax):
| Type (posted rate) | Pre-tax interest (KRW) | After-tax (KRW) | Vs. RP type (KRW) |
|---|---|---|---|
| RP, 2.30% | 18,904 | 15,993 | baseline |
| Issued note, 2.60% | 21,370 | 18,079 | +2,086 |
| MMF, 2.58% | 21,205 | 17,940 | +1,947 |
| MMF, 2.92% | 24,000 | 20,304 | +4,311 |
The arithmetic is 10,000,000 × rate × 30/365 × 0.846. Switching types buys between 2,000 and 4,300 won after tax over 30 days, or 25,000 to 52,000 won stretched across a year. Whether that compensates for taking on one more layer of issuer credit risk is the entire decision. And because the issued-note 2.60% is a one-day rate, leaving the money for 30 days will likely realize less than the table shows.
Earning an extra 0.3 percentage points in a CMA means buying one notch of issuer credit risk for 2,086 won after tax, on 10 million won over 30 days.
What to Watch
- The period condition next to the posted rate — whether your holding period lands in the day-1, days-1-to-30, or day-31-onward bracket. The footnote sets the real return.
- For issued-note types, the issuing brokerage's credit rating — with no deposit insurance, the issuer's balance sheet is the only remaining backstop.
- Withdrawal timing — MMF alone settles next day, which rules it out for settlement float.
- What the 100 million won ceiling covers — bank and savings-bank deposits, not CMA balances. That changes where you draw the line when splitting cash reserves.
- Whether it is a jonggeum type — the only insured CMA, though few firms offer it and the posted rate needs checking on its own terms.
