How we verify rates and estimate what you keep

Where rates come from

Treasury yields come from the U.S. Treasury's daily par yield curve, pulled automatically every weekday evening. If a rate moves more than a full point overnight, it's held back until confirmed.

Every other rate is read from the provider's own rate page, rate sheet or fund page, and listed with that date. News stories, forums and comparison sites tell us something changed; they're never the source of a number. A provider whose page we can't read isn't listed. We list each account type separately, because self-directed, advisor-led, advisory and IRA accounts at the same firm often pay very different rates.

What each number means

Rate, verified: the rate on the provider's page, for the balance tier noted, on the date shown.
Gross per year at today's rate: your balance times that rate. Rates change, so this is a snapshot, not a forecast.
Estimated after tax: gross earnings minus estimated taxes at the settings you enter (below).
Access, conditions, protection: how quickly you can use the money at full value, what it takes to get the rate, and what protects it.
Estimated advantage: the after-tax difference from the option you say your cash sits in now. It's an estimate at today's rates, not a guaranteed saving.

Tax assumptions (2026 tax year)

• Interest is taxed at the federal bracket you choose, as your top marginal rate. We don't model brackets in between.
• State tax uses the single rate you enter. We don't subtract state tax on your federal return, since most high earners are at the cap on that deduction.
• Treasury bill and note interest is exempt from state and local income tax.
• A money market fund passes through state exemption only on the share of its income from U.S. government obligations, published in the fund company's annual tax notice. California, Connecticut and New York allow it only if the fund held at least 50% of its assets in those obligations; we approximate that with the income share.
• Municipal money funds are free of federal income tax and the 3.8% surtax, and usually taxed by your state unless they hold only your state's bonds.
• IRA interest isn't taxed each year, so IRA options are compared only with other IRA options.
• Account fees (for example, a subscription required for a rate) and advisory fees come off after tax; they aren't deductible.

The 3.8% net investment income tax

It applies only if your modified adjusted gross income is over $200,000 (single), $250,000 (married filing jointly) or $125,000 (married filing separately). It's charged on the smaller of your net investment income or the amount you're over the threshold, so it may apply to only part of your interest. It's off by default; turn it on only if it applies to you, and check with your tax preparer.

State-exempt shares we use

• Fidelity brokerage (SPAXX core) (SPAXX, Fidelity Government Money Market): 0.00%. Part of SPAXX's income is likely state-exempt, but we haven't verified Fidelity's tax notice yet, so we treat it as fully state-taxable.
• Vanguard brokerage (VMFXX, Vanguard Federal Money Market (settlement fund)): 66.61%, from the 2025 tax notice.
• Treasury-only money fund (FSIXX, Fidelity Treasury Only Portfolio, on Merrill): 100.00%. Holds only U.S. Treasuries, so its income should be fully state-exempt. We haven't linked Fidelity's own tax notice yet; Vanguard's comparable Treasury-only fund (VUSXX) reported 100% for 2025.
• Prime money fund (SWVXX, Schwab Prime Advantage Money Fund): 0.00%. Holds corporate and bank debt, so its income is fully taxable by your state.
• Municipal money fund (not your state's) (FFTXX, Federated Hermes Institutional Tax-Free Cash Trust, on Merrill): 0.00%. Free of federal tax and the 3.8% surtax. Usually taxable by your state unless the fund holds only your state's bonds.

FDIC rules in our calculator

We apply the FDIC's per-depositor, per-bank, per-ownership-category limits, including the trust rule in effect since April 1, 2024: $250,000 per owner per distinct eligible beneficiary, capped at $1.25 million per owner across all trust accounts at one bank. Trust deposits with no eligible beneficiary count as single deposits. Coverage is per chartered bank, not per brand. For complex cases, the FDIC's Electronic Deposit Insurance Estimator is the definitive tool.

Coverage, and what's missing

We currently list 27 options from 19 providers. Not listed yet: UBS (rate table loads in a frame our browser couldn't read); J.P. Morgan Self-Directed Investing (site blocked for automated reading on 10/23); LPL Financial (rate pdf is an image); Fidelity Cash Management Account (rate didn't render); Betterment Cash Reserve (site blocked for automated reading on 10/23); Capital One 360 Performance Savings (rate didn't render); Webull, Public, SoFi Invest, Ally Invest (not checked yet).

Every source, with its date