Money Market Account vs Treasury Bills: Where to Park Your Short-Term Cash

Fact-checked by the The Finance Tree editorial team

The money market vs treasury bills debate comes down to a clear trade-off: liquidity versus yield. Money market accounts (MMAs) are bank-held, FDIC-insured accounts with instant access to your funds, while Treasury bills are short-term U.S. government debt securities that typically pay slightly higher rates. According to FDIC deposit rate data, the highest-yielding MMAs currently sit near 5.00% APY — competitive, but still below the yields on short-duration T-bills at many tax brackets.

With the Federal Reserve holding its benchmark rate steady in 2025, both options remain attractive for parking short-term cash. Knowing the distinction can meaningfully affect your after-tax return.

How Do Money Market Accounts Work?

A money market account is an interest-bearing deposit account held at a bank or credit union, insured by the FDIC (or NCUA for credit unions) up to $250,000 per depositor. It combines features of a savings account and a checking account, offering check-writing and debit access while earning a competitive rate.

MMAs are straightforward to open and require no brokerage account. Rates are variable, meaning the bank can adjust them at any time. The best nationally available MMAs from institutions like Ally Bank, Marcus by Goldman Sachs, and Discover Bank currently offer yields near or above 4.50% APY, according to Bankrate’s current MMA rate survey.

Key Features of Money Market Accounts

• FDIC or NCUA insured up to $250,000
• Variable interest rate — can rise or fall with the Fed
• Immediate liquidity — withdraw any time
• No auction process or secondary market needed
• Interest is taxable at federal, state, and local levels

One underappreciated downside: MMA interest is fully taxable at all levels. For earners in high-tax states like California or New York, this erodes the effective yield noticeably compared to T-bills.

How Do Treasury Bills Work?

Treasury bills are short-term debt instruments issued by the U.S. Department of the Treasury with maturities ranging from 4 weeks to 52 weeks. You buy them at a discount and receive face value at maturity — the difference is your return.

T-bills are sold via weekly auctions on TreasuryDirect.gov or through brokerage platforms like Fidelity, Charles Schwab, and Vanguard. As of July 2025, the 4-week T-bill yield sits near 5.25%, and 13-week bills are yielding approximately 5.20%. These rates reset at each auction, so they track the federal funds rate closely.

State Tax Exemption — A Meaningful Advantage

T-bill income is exempt from state and local income taxes under federal law. For a resident of New York City paying a combined state and local rate near 12%, this exemption can add the equivalent of 60+ basis points to the effective yield — a significant edge in the money market vs treasury bills comparison.

The practical friction: T-bills require a brokerage or TreasuryDirect account, and your cash is locked until maturity (though T-bills can be sold on the secondary market before maturity).

Money Market vs Treasury Bills: How Do They Compare Side by Side?

The right choice depends on four variables: your tax bracket, your state tax rate, your need for liquidity, and the size of your cash position. Here is a direct comparison of the two vehicles across the most important decision factors.

For most savers with less than $10,000 to park and a need for ongoing access — say, a sinking fund for a planned purchase — an MMA is simpler and equally safe. For larger cash positions, especially in high-tax states, T-bills offer a better after-tax outcome in the money market vs treasury bills equation.

Which Is Better for Your Situation?

Your ideal choice in the money market vs treasury bills comparison depends on three practical questions: How soon might you need the money? What is your combined state and federal tax rate? And how much friction are you willing to accept?

If you are building an emergency fund or need funds available within days, a money market account is the right tool. There is no auction schedule, no maturity date, and no secondary market to navigate. If you are parking a quarterly tax payment, a bonus, or proceeds from a home sale for 4 to 13 weeks, T-bills are worth the modest setup effort.

Tax Bracket Math

Assume you are in the 24% federal bracket and a state with a 6% income tax. On an MMA paying 5.00%, your after-tax yield is roughly 3.50%. On a T-bill paying 5.25%, exempt from state tax, your after-tax yield is approximately 3.81%. That gap widens further in high-tax states. You can model this using the IRS guidance on interest income taxation.

If you are working toward broader financial goals in your 30s, optimizing even your short-term cash can accelerate your timeline. Additionally, reducing unnecessary fees from your banking relationships — such as those covered in our guide to hidden bank fees that drain your account — can matter as much as yield optimization.

Are There Risks to Either Option?

Both money market accounts and Treasury bills are among the lowest-risk instruments available to retail investors, but they are not identical in their risk profiles.

MMAs carry bank default risk above the $250,000 FDIC limit. Below that threshold, the risk is negligible — but savers with more than $250,000 in a single institution should structure accounts across multiple banks or account types. T-bills carry the full faith and credit of the U.S. government and are considered the closest thing to a risk-free asset in global finance, as recognized by the Federal Reserve’s H.15 release on selected interest rates.

A secondary risk for T-bills is reinvestment risk: when your bill matures, the next auction may offer a lower rate if the Fed has cut rates. MMAs carry the same risk in a different form — the bank simply reduces your rate at any time without notice. For those also tracking overall financial health, understanding your full balance sheet through net worth tracking can help you allocate cash more intentionally.

Frequently Asked Questions

Is a money market account or Treasury bill better for an emergency fund?

A money market account is better for an emergency fund because it offers immediate access to your cash with no maturity date. T-bills lock your money for 4 to 52 weeks, and while they can be sold on the secondary market, that adds friction and potential price risk you do not want in an emergency.

Do Treasury bills beat money market accounts after taxes?

In most cases, yes — especially for investors in states with income taxes above 5%. The state and local tax exemption on T-bill income can add 30 to 80 basis points to the effective after-tax yield. Run the calculation using your combined federal and state marginal rate to confirm the advantage in your specific situation.

Can I lose money in a money market account?

Not if your balance is under the FDIC limit of $250,000 per depositor, per institution. The FDIC guarantee makes money market account losses virtually impossible within that threshold. Above $250,000, you should spread deposits across multiple FDIC-insured institutions.

How do I buy Treasury bills without a brokerage account?

You can purchase T-bills directly through TreasuryDirect.gov, the U.S. Treasury’s official platform, with a minimum purchase of just $100. You will need a U.S. bank account to fund the purchase and receive proceeds at maturity. Most major brokerages also offer T-bill purchases with no transaction fee.

What happens to T-bill and MMA rates if the Fed cuts rates?

Both fall. MMA rates are adjusted almost immediately by banks following a Fed rate cut. T-bill rates reset at the next weekly auction, reflecting the new rate environment. If you lock in a T-bill at today’s rate and the Fed cuts before maturity, your bill continues to pay the original yield — a short-term advantage over the variable MMA.

Is the money market vs treasury bills decision different for large cash positions?

Yes, significantly. For cash above $250,000, T-bills offer an additional advantage: full government backing with no cap, unlike the FDIC limit on MMAs. Large cash holders — businesses, retirees, real estate sellers — often prefer T-bills specifically because of this uncapped safety and the state tax exemption layered on top.