Editorial note: the first-person examples below are illustrative scenarios built from common real-world situations, used to show the arithmetic step by step. They are not a claim about the author's personal financial history.
Three Accounts, One Decision
Cash is the least interesting part of personal finance and the part people get wrong most often. As of 2026, FDIC-insured online banks have been paying roughly 3.5–5% APY while the average brick-and-mortar savings account pays closer to 0.4%, according to FDIC national rate data. On $25,000, that gap is the difference between about $100 a year and about $1,100 a year — for the same deposit insurance and the same twenty minutes of work.
The three accounts people compare — high-yield savings (HYSA), certificates of deposit (CD), and money market accounts — are not really competitors. They solve different problems: access, rate certainty, and convenience. Once you separate those, the allocation decision takes about five minutes.
What Each Account Actually Is
| Account | Rate type | Access | Insured? | Best for |
|---|---|---|---|---|
| High-yield savings | Variable APY | Anytime, usually free transfers | FDIC/NCUA up to $250,000 | Emergency fund, short-term goals |
| CD | Fixed APY for a term | Locked; penalty to exit early | FDIC/NCUA up to $250,000 | Money with a known date |
| Money market account (bank) | Variable, often tiered | Limited check writing, ATM | FDIC/NCUA up to $250,000 | Cash you also need to spend from |
| Money market fund (brokerage) | Variable, tracks short rates | T+1 settlement | SIPC, not FDIC | Larger balances, brokerage cash |
That last row is where most confusion lives. A money market account at a bank is a deposit. A money market fund at a brokerage is a mutual fund holding short-term debt — the SEC explains the difference, including the fact that a fund’s $1 share price is not guaranteed. Yields on funds often run slightly above bank savings because there is no insurance and no bank overhead.
The Liquidity Ladder
The practical framework is a ladder, not a choice:
- One month of expenses in checking. Boring, near-zero yield, and the reason you never overdraft.
- Three to six months of necessary expenses in an HYSA. This is the emergency fund. It must be liquid and insured — see our emergency fund guide for how to size it.
- Money with a known date in a CD. Tuition due in 14 months, a roof replacement next spring, a tax bill you already know the size of.
- Everything above that, if you want a slightly better yield, in a laddered CD or Treasury bills.
The order matters. People who chase CD rates before funding step two end up breaking a CD — and paying a penalty — the first time a transmission fails.
The Yield Math on Real Balances
A CD paying 4.60% instead of a savings account paying 4.10% looks like a rounding error. It is, until you scale it:
| Balance | HYSA at 4.10% | CD at 4.60% | Extra |
|---|---|---|---|
| $5,000 | $205/yr | $230/yr | $25 |
| $25,000 | $1,025/yr | $1,150/yr | $125 |
| $100,000 | $4,100/yr | $4,600/yr | $500 |
Half a percentage point on $100,000 is $500 a year — worth a twenty-minute decision. Half a percentage point on $5,000 is $25, which is not worth locking your money for twelve months. This is the entire argument for keeping the emergency fund liquid: the yield premium is too small to justify the penalty risk.
The CD Trap Nobody Mentions
Two risks hide inside a “safe” CD.
Reinvestment risk at maturity. A 12-month CD at 4.60% feels like a win until it matures in a rate-cutting cycle and the next one pays 3.20%. You locked the rate for a year, not forever. That is why ladders exist: five CDs maturing in consecutive years mean only one-fifth of your cash reprices in any given year.
Early withdrawal penalties. Most banks charge three to six months of interest, and some charge more. The penalty can exceed the interest earned if you break the CD early, which means a “4.60% APY” can net you less than the savings account you left. Read the specific penalty formula before you open one — “3 months interest” and “180 days simple interest” are not the same number.
The Tax Detail That Favors Treasuries
Interest from a savings account, CD, or money market fund is taxed as ordinary income — federal and, generally, state. That is IRS Publication 550 territory, and it is why a 4.5% CD in a 24% federal bracket plus a 5% state bracket is really a 3.2% after-tax return.
Short-term Treasury bills are exempt from state and local income tax. In a high-tax state, a 4.3% T-bill can beat a 4.5% CD on an after-tax basis. TreasuryDirect sells them directly with no fee, in $100 increments. If you hold a large cash position in a state with income tax, run both numbers before assuming the CD wins.
What I Actually Do With My Own Cash
I keep roughly four months of expenses — about $19,000 — in an online savings account at 4.15%, and I do not touch it. Above that, I run a three-rung CD ladder with $12,000 total, one rung maturing every four months, currently averaging 4.45%. The remaining $6,000 sits in a Treasury bill ladder because I live in a state with a 5% income tax and the state exemption is worth more than the extra 0.2% a CD would pay.
The whole structure took about 90 minutes to set up across three institutions, and it has required maybe fifteen minutes of maintenance a year — rolling a maturing rung, updating a rate. The yield difference versus leaving everything in my old checking account is roughly $1,700 a year. That is not a side hustle, and it is not passive income; it is just not leaving money on the table. If you want the fuller picture of how cash fits with invested money, our investing basics guide covers what should sit above the cash layer.
When Each One Wins
- HYSA wins when you need access within days, when rates are rising (variable APY reprices upward), or when the balance is small enough that a rate premium is trivial.
- CD wins when you have a known date and rates are near a peak, or when the psychological lock stops you from spending the money.
- Money market account wins when you want a single account for both saving and occasional spending — checks, ATM, and a better rate than regular savings.
- Money market fund or T-bills win when the balance is large and you can tolerate T+1 access, or when state tax makes the exemption valuable.
The Bank Health Check Before You Move Money
An extra 0.40% on $40,000 is $160 a year. A bank failure with uninsured deposits is $40,000. The order is: confirm the insurance, then compare the rate.
FDIC coverage is $250,000 per depositor, per bank, per ownership category. A single account and a joint account at the same bank are separate categories, so one person can hold $250,000 individually plus $250,000 as their share of a joint account at the same institution. Retirement accounts held at a bank are insured separately up to $250,000. Credit unions are covered by the NCUA on the same terms.
Verify, do not assume. Use FDIC BankFind to confirm the institution is insured and to see its official name. Fintech apps frequently hold customer cash at a partner bank, and the deposit is insured under that bank’s name, not the app’s. That structure works — until it does not. When a middleware provider failed in 2024, thousands of customers could not access balances for months even though the underlying deposits were ultimately recoverable. Convenience products are not the same as a bank account.
Brokerage cash is a different animal. SIPC protects securities if a broker fails, not the cash balance itself. Cash held in a money market fund is a security and carries the fund’s own risk profile; cash swept to a program bank may be FDIC-insured up to the limit. Read the sweep disclosure rather than assuming.
Above $250,000, use ownership categories or separate banks. Joint accounts, payable-on-death designations, and trust titling each create additional coverage. For a large cash position, the simplest approach is usually two or three institutions rather than a complicated titling strategy.
Watch what the yield is attached to. A rate 1.5 points above every competitor is either a promotional period with a short end date, a deposit requirement, or a product that is not actually a deposit account. Read the account agreement for the minimum balance required to earn the advertised rate — a 4.5% APY that drops to 0.05% below a $25,000 balance is a 0.05% account for anyone who dips.
The Bottom Line
Fund the emergency fund in a high-yield savings account first, then ladder surplus cash into CDs or Treasuries with maturities that match real expenses. Check the early-withdrawal penalty before you sign, check whether the rate is fixed or variable, and remember that a bank money market account and a brokerage money market fund are different products with different protections. The gap between a 0.4% account and a 4.2% account is not a clever strategy — it is the single easiest dollar-for-dollar improvement available to most households, and it takes one afternoon.
Sources & References
- FDIC — National Rates and Rate Caps — current national deposit rate data
- FDIC — Deposit Insurance FAQs — the $250,000 coverage limit and ownership categories
- NCUA — Share Insurance — equivalent coverage at credit unions
- SEC Investor.gov — Money Market Funds — why funds differ from insured deposits
- TreasuryDirect — Treasury Bills — how T-bills are sold and their state-tax treatment
- IRS Publication 550 — Investment Income and Expenses — taxation of interest income