Treasury Bills vs High-Yield Savings Accounts: Where Should Your Cash Go?

You’ve got a chunk of cash sitting there, maybe a few thousand dollars, maybe more, and you’re wondering where it should actually live. Should you park it in a high-yield savings account, or lock it into Treasury bills for a few months? Both options sound smart, but the right answer depends on details most people skip right over.

Top high-yield savings accounts from institutions like SoFi, Ally Bank, and Marcus by Goldman Sachs are paying in the range of 4.1–4.5% APY, while 3-month T-bills issued by the U.S. Department of the Treasury have been hovering around 4.3–4.6%, sometimes higher, sometimes slightly lower, depending on where the Federal Reserve has the federal funds rate. This article breaks down the real differences so you can make the call that fits your situation, not just chase the highest number on paper.

What Are Treasury Bills, Exactly?

Treasury bills (T-bills) are short-term debt securities issued by the U.S. Department of the Treasury. They come in terms of 4, 8, 13, 17, 26, and 52 weeks. You buy them at a discount and receive the full face value at maturity, that difference is your interest.

You can buy T-bills directly through TreasuryDirect.gov with no fees, or through a brokerage account such as Fidelity, Charles Schwab, or Vanguard. The minimum purchase is $100. Because they’re backed by the full faith and credit of the U.S. government, they carry zero default risk in any practical sense. Weekly T-bill auctions are administered by the Federal Reserve Bank of New York on behalf of the Treasury, and results are published publicly within hours of each auction closing.

T-bills are distinct from other Treasury securities like Treasury Notes (T-notes, which mature in 2–10 years) and Treasury Bonds (T-bonds, which mature in 20–30 years). For cash management purposes, T-bills are the instrument of choice because their short durations minimize interest rate risk while still delivering competitive yields.

One real limitation worth naming: once you buy a T-bill, that money is committed until maturity. Selling early on the secondary market is possible, but it adds friction and a small risk of receiving less than expected. If there’s any chance you’ll need the cash before the bill matures, that matters.

What Are High-Yield Savings Accounts?

A high-yield savings account (HYSA) is a savings account, typically offered by online banks, that pays a much higher interest rate than a traditional bank account. Where a standard savings account at a brick-and-mortar institution like JPMorgan Chase or Bank of America might offer 0.01–0.10% APY, top HYSAs from online-first banks have been paying 4–5% APY in recent years.

Deposits are FDIC-insured up to $250,000 per depositor per bank. The Federal Deposit Insurance Corporation (FDIC) has backed depositors since 1933 without ever failing to pay out on an insured account. The big draw is flexibility: you can deposit or withdraw money whenever you need it, with no lock-in period. Our full breakdown of high-yield savings accounts covers the current top rates and which banks are worth considering.

Major HYSA providers include SoFi, Ally Bank, Marcus by Goldman Sachs, Discover Bank, American Express National Bank, and Synchrony Bank. Each is FDIC-insured and competes aggressively on rate. The Consumer Financial Protection Bureau (CFPB) requires these institutions to disclose their APY clearly and to provide advance notice before changing account terms, though rate changes themselves can happen with minimal lead time. That last point is the core tradeoff: you get full liquidity, but you don’t control the rate you’ll earn six months from now.

Treasury Bills vs High Yield Savings: Key Differences

Liquidity

On liquidity, savings accounts win outright. Your cash is available on demand, no holding periods, no penalties. T-bills have a fixed maturity date, so accessing money early means selling on the secondary market, which adds friction and a small risk of selling at a slight discount.

For your emergency fund, liquidity matters a lot. A savings account keeps that money truly accessible. If you’re trying to decide how much cash to keep on hand versus invest, building a personal financial system is a useful framework for thinking through the whole picture.

Interest Rate Risk

HYSA rates are variable. When the Federal Reserve cuts the federal funds rate, banks lower their savings rates, sometimes quickly. T-bill rates are locked in at the time of purchase. Buy a 26-week T-bill at 4.5%, and you get 4.5% for that full period regardless of what the Fed does next.

This rate certainty makes T-bills appealing when rates are expected to fall. You’re locking in today’s yield for months ahead. The Federal Open Market Committee (FOMC), which sets the federal funds rate, meets approximately eight times per year. Each meeting is a potential catalyst for HYSA rate changes but has no effect on T-bills you already hold.

Tax Treatment

This is where T-bills have a quiet but real advantage. T-bill interest is exempt from state and local income taxes. HYSA interest is fully taxable at the federal, state, and local level. If you live in a high-tax state like California (13.3% top marginal rate) or New York City (where combined state and city taxes can exceed 14%), that exemption adds meaningful value to your after-tax return. The IRS classifies T-bill discount income as interest income reported on Form 1099-INT, and your state return simply excludes it.

The math is straightforward: a T-bill yielding 4.5% can beat a HYSA yielding 4.7% once you factor in state taxes. Run the numbers for your state before deciding which comes out ahead.

Treasury Bills vs High-Yield Savings Accounts: Side-by-Side Comparison

The table below compares the two options across the dimensions that matter most to everyday savers. Use this as a quick reference before diving into the section-by-section analysis.

Who Should Choose Treasury Bills?

T-bills make sense when you have cash you won’t need for a defined period. Think: money earmarked for a down payment in six months, a tax payment due in a quarter, or savings you want to park somewhere safe with a predictable return. They’re also worth considering if you’re in a high-tax state and want to minimize your tax bill on interest income.

Investors already comfortable with basic brokerage accounts often find T-bills easy to manage. Many brokerages, including Fidelity, Charles Schwab, and Vanguard, allow auto-roll, automatically reinvesting into a new T-bill when the current one matures. That removes much of the manual effort and keeps your cash working without interruption. If you’re thinking about your broader investment strategy, our guide to index funds vs. ETFs is a natural next step once your cash is optimized.

Self-employed individuals, freelancers, or business owners who set aside estimated quarterly tax payments are particularly well-served by T-bills. A 13-week T-bill matures in roughly the same time frame as the IRS quarterly estimated tax schedule, making it a near-perfect fit for holding money that’s earmarked for the IRS but shouldn’t sit idle in a checking account.

That said, T-bills do require slightly more effort to set up than opening a savings account. New buyers sometimes find the auction process unfamiliar, and TreasuryDirect’s interface is not exactly intuitive. The learning curve is short, but it exists.

Who Should Choose a High-Yield Savings Account?

Your emergency fund belongs in a savings account. Full stop. The whole point of an emergency fund is that you can get to it fast when something goes wrong. A T-bill with two months left to maturity doesn’t help when your car breaks down today.

Savings accounts also work better for people who aren’t sure exactly when they’ll need the money. Variable income, irregular expenses, or just general unpredictability? Keep that cash accessible. The slightly lower after-tax yield is worth the peace of mind and flexibility. If you’re working through a financial setback, handling a financial setback without resetting your plan has some grounded advice on keeping your cash strategy steady.

For savers who are still building their emergency reserves and making regular deposits, the frictionless nature of HYSAs from institutions like Ally Bank, SoFi, or American Express National Bank is a meaningful practical advantage. T-bill auctions happen weekly, so you’d be buying new bills each time you accumulate enough, manageable, but more cumbersome than simply depositing money into a savings account whenever you have it.

The rate variability is the real cost. When the Fed cuts, your HYSA rate follows. Savers who locked into T-bills before a rate cut cycle consistently came out ahead of those who stayed variable, that’s not hypothetical, it’s what happened to anyone paying attention after late 2024.

Treasury Bills vs High Yield Savings: Which Actually Pays More?

On a raw rate basis, the two options are often close. But “close” doesn’t mean equal once you do the full math. State tax exemption on T-bills can tip the scales, especially for those in high-tax states. Always compare the after-tax yield, not just the headline rate.

Here’s a quick way to calculate the equivalent taxable yield for a T-bill:

• Find your combined state and local tax rate (e.g., 8%)
• Divide the T-bill yield by (1 minus your state tax rate): 4.5% ÷ 0.92 = 4.89%
• If your HYSA pays less than 4.89%, the T-bill wins on after-tax income

The FDIC’s bank data and Treasury’s published interest rate data are both public and regularly updated, use them to compare live rates before you decide. And if you want context on how small rate differences compound over time, how compound growth rewards boring decisions puts the math in perspective.

How the Fed Rate Environment Affects Your Decision

The Federal Reserve’s rate trajectory is one of the most important contextual factors when choosing between T-bills and HYSAs. The direct answer: when rates are falling, locking in a T-bill is generally smarter; when rates are rising, HYSA flexibility lets you capture higher rates as they climb.

The Federal Open Market Committee (FOMC) began a rate-cutting cycle in late 2024 after holding the federal funds rate at a 23-year high. The current federal funds rate target range reflects a more accommodative stance than the peaks of 2023. This environment creates a real incentive to lock in T-bill yields rather than leave money in a savings account that will reprice lower each time the Federal Reserve cuts.

When the Fed raised rates aggressively in 2022 and 2023, staying variable in a HYSA was the clear winner for active savers, rates were climbing weekly, and capturing every increment mattered. That dynamic has shifted. In a declining or plateauing rate environment, the T-bill rate-lock becomes a genuine advantage, not a minor technicality.

Watch the Federal Reserve’s H.15 release, published weekly, which tracks selected interest rates including Treasury securities. Comparing the 3-month T-bill yield against the top HYSA rates from Bankrate or NerdWallet‘s rate trackers gives you a current, side-by-side snapshot before you commit.

The T-Bill Ladder Strategy: Getting Liquidity Without Sacrificing Yield

One of the most practical ways to use T-bills without sacrificing flexibility is to build a T-bill ladder. Staggering maturity dates means a portion of your cash becomes available at regular intervals, giving you scheduled liquidity without needing to sell early.

Here’s how it works in practice:

• Divide your total cash allocation into equal portions, say, four equal parts of $5,000 each from a $20,000 pool.
• Buy a 4-week T-bill, an 8-week T-bill, a 13-week T-bill, and a 26-week T-bill simultaneously.
• Every four weeks, one T-bill matures. You can use the cash or reinvest into a new 26-week bill to keep the ladder rolling.
• Over time, you’re capturing the yield of longer-term T-bills while having $5,000 come available every month.

This strategy is available to anyone with a TreasuryDirect account or a brokerage account at Fidelity, Charles Schwab, or Vanguard. Many brokerages have made building T-bill ladders nearly automated through their fixed income tools. It’s an approach historically used by institutional treasury desks at corporations like Berkshire Hathaway, which famously holds tens of billions in short-term Treasuries, and it scales down effectively for individual savers.

What About Money Market Funds?

Worth knowing: there’s a third option that often gets overlooked in the T-bill vs. HYSA debate. Money market funds are mutual funds that invest primarily in short-term government securities, including T-bills, and aim to maintain a stable $1.00 net asset value (NAV).

Government money market funds from providers like Fidelity (e.g., SPAXX), Vanguard (e.g., VMFXX), and Charles Schwab (e.g., SNVXX) currently yield in the 4.0–4.4% range. They offer same-day liquidity like a HYSA and partial state tax exemption (since they hold mostly government securities), though the exemption isn’t always as clean as direct T-bill ownership.

Money market funds are not FDIC-insured, but government money market funds are considered extremely safe, they invest in securities backed by the U.S. government. The Securities and Exchange Commission (SEC) regulates them under Rule 2a-7, which imposes strict requirements on the quality, maturity, and liquidity of their holdings.

For savers who want T-bill-like yields with HYSA-like liquidity and don’t want to manage individual auctions, a government money market fund sitting inside a brokerage account is often the best compromise.

State-by-State Tax Impact on Your Real Return

The state tax exemption on T-bill interest is the most consistently underestimated factor in this comparison. The higher your state income tax rate, the more T-bills outperform HYSAs on an after-tax basis, often by a full half-percentage point or more.

The following illustrates the after-tax T-bill equivalent yield at a 4.5% T-bill rate, compared to what a HYSA paying 4.3% APY actually nets you after state taxes:

Note: These calculations assume you are at the top marginal state bracket. Your actual rate may be lower. Consult a tax professional or use your state’s tax authority’s published rate schedule for a precise calculation. New York City residents should add approximately 3.876% in city taxes to the state rate, widening the T-bill advantage further.

Can You Use Both?

Yes, and for many people, using both makes the most sense. Keep three to six months of expenses in a HYSA for true liquidity. Then use T-bills for any cash beyond that: savings with a clear timeline, a future large purchase, or money that can sit untouched for a few months.

This isn’t complicated. It’s matching the right tool to the right job. Splitting your cash across both accounts means you’re not sacrificing yield for liquidity or liquidity for yield. A practical starting framework: your HYSA holds the emergency fund and any cash you might need within 30 days; T-bills (or a T-bill ladder) hold everything else with a defined or flexible-but-not-urgent timeline.

If your total liquid savings exceed $250,000, the calculus tilts more clearly toward T-bills for the excess. FDIC insurance caps out at $250,000 per depositor per bank (though you can spread across multiple banks to multiply coverage). T-bills carry no such cap, the full faith and credit of the U.S. government backs every dollar, regardless of amount.

Frequently Asked Questions

Are Treasury bills safer than high-yield savings accounts?

Both are extremely safe, but in different ways. T-bills are backed by the U.S. government, which has never defaulted on its debt. Deposits in HYSAs are FDIC-insured up to $250,000 per depositor per bank. For amounts under $250,000, the risk difference is negligible for most savers. Above that threshold, T-bills have a slight edge since there’s no coverage cap.

How do I buy Treasury bills?

You can buy T-bills directly from the U.S. Treasury through TreasuryDirect.gov with no fees and a $100 minimum. You can also buy them through any major brokerage account, Fidelity, Charles Schwab, Vanguard, often with more convenience features like auto-roll. Auctions happen weekly, so you’re never waiting long to get in.

What happens to my T-bill rate if the Fed cuts interest rates?

Nothing changes for your existing T-bill. The rate is locked in at purchase. When you go to reinvest at maturity, however, the new T-bill rate will reflect the current rate environment. This is why locking in a longer-term T-bill (like 26 or 52 weeks) can be advantageous when rates are expected to decline.

Is the interest on Treasury bills taxed?

T-bill interest is subject to federal income tax but is exempt from state and local income taxes. HYSA interest is taxed at all three levels, federal, state, and local. The IRS requires interest from both to be reported; T-bill interest appears on Form 1099-INT issued by TreasuryDirect or your brokerage. Depending on where you live, this difference can meaningfully affect your after-tax return. Always compare after-tax yields, not just headline rates.

Should my emergency fund be in a HYSA or T-bills?

Your emergency fund belongs in a HYSA. Emergency funds need to be accessible immediately, T-bills have maturity dates and can’t be liquidated instantly without some hassle. The slightly lower after-tax yield is worth the full liquidity. Use T-bills for money you know you won’t need for weeks or months.

What is the minimum amount needed to buy a Treasury bill?

The minimum purchase for a T-bill through TreasuryDirect.gov is $100, in increments of $100. Most major brokerages like Fidelity and Charles Schwab also allow T-bill purchases with the same or similar minimums. There is no maximum limit for non-competitive bids in Treasury auctions.

How does FDIC insurance work for high-yield savings accounts?

The Federal Deposit Insurance Corporation (FDIC) insures deposits up to $250,000 per depositor, per FDIC-insured bank, per ownership category. Joint accounts receive up to $500,000. If you have more than $250,000 to protect, you can spread deposits across multiple FDIC-insured banks to extend coverage, or use T-bills, which carry no coverage cap.

Can T-bills and HYSAs be used together?

Yes, and that combination works well for most savers. Keep your emergency fund and near-term spending in a HYSA for instant access. Put cash with a known timeline, a tax payment, a down payment, a planned large expense, into T-bills to lock in the yield. You get liquidity where it matters and rate certainty where it doesn’t.

Do T-bill yields move with the federal funds rate?

Closely, but not identically. Short-term T-bill yields are heavily influenced by market expectations for the federal funds rate. When the Fed signals rate cuts ahead, T-bill yields often fall before the actual cut occurs. This is why acting before a cutting cycle is well underway typically captures better yields than waiting.

What are the tax reporting requirements for T-bill interest?

TreasuryDirect and your brokerage will issue a Form 1099-INT each year showing the interest earned on T-bills. You report that amount as ordinary income on your federal return. On your state return, T-bill interest is excluded, most state tax software handles this automatically, but confirm your state’s specific treatment, particularly if you hold T-bills through a money market fund rather than directly.