High Yield Savings Account vs. Treasury Money Market Calculator
Tuesday, November 3, 2026
When you’re deciding where to keep your cash, the account with the highest advertised interest rate isn’t always the one that earns you the most money.
High-yield savings accounts (HYSAs) and Treasury money market funds are great places to put your cash but they are taxed differently. And based on your tax rates, that difference can make a Treasury money market fund more rewarding.
Our Tax-Equivalent Yield Calculator helps you compare the two options based on how much money you’ll actually keep after taxes.
Enter the amount you plan to save or invest, the interest rate on your high-yield savings account, and the yield on a Treasury money market fund.
Next, enter your federal marginal income tax rate and your combined state and local income tax rate. You can also adjust the percentage of the Treasury fund’s income that’s exempt from state income taxes.
The calculator will show you:
This makes it easier to compare the two options on an apples-to-apples, after-tax basis.
Find out which option could earn you more after federal, state, and local income taxes.
Treasury money market comes out ahead
Estimated annual results using the yields you entered.
HYSA after-tax yield
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Estimated after-tax income / year
Treasury fund after-tax yield
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Estimated after-tax income / year
Estimated annual advantage
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Estimates assume unchanged annualized yields and marginal tax rates. HYSA APY includes compounding, while a fund’s 7-day SEC yield is a recent annualized income measure; they are not identical. Calculations use a simplified additive federal and state/local tax model and exclude NIIT, federal deductibility of state taxes, other tax interactions, and any additional fees. Treasury fund distributions may only be partially state-tax exempt and some states impose minimum-holding requirements. This calculator is educational, not tax advice.
Interest earned in a high-yield savings account is generally subject to federal income tax as well as applicable state and local income taxes.
Interest earned directly from U.S. Treasury securities is subject to federal income tax but generally exempt from state and local income taxes.
Treasury money market funds invest in short-term Treasury securities and other highly liquid investments. Depending on the fund’s holdings, some or all of the income distributed by the fund may qualify for that same state and local tax exemption.
For example, suppose you’re comparing:
Assuming the Treasury fund’s income is entirely exempt from state and local income taxes, the HYSA’s estimated after-tax yield would be 2.72%, while the Treasury fund’s would be 2.89%.
The Treasury fund’s tax-equivalent yield would be approximately 4.25%. In other words, you’d need a
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