Treasury Bills: The Savings Account Alternative Nobody Told You About

There’s a savings tool that’s been sitting in plain sight the whole time: issued by the U.S. Treasury, backed by the full faith and credit of the federal government, exempt from state income tax, and available in terms as short as four weeks. Almost nobody outside the bond world used to bother with it. Then rates rose, everyone got curious about yield, and suddenly Treasury bills became the least glamorous way to earn a competitive return on cash.

This post is the walkthrough I’d want before my first purchase: what T-bills are, how you actually buy one, what the interest looks like in dollars, and — more important — when the extra complexity isn’t worth it, because there are absolutely cases where I’d keep the simple savings account.

What a Treasury Bill Actually Is

A T-bill is a short-term loan to the U.S. government. You don’t receive interest payments along the way; instead you buy the bill at a discount and the Treasury pays you face value at maturity. Buy a $10,000 bill for less than $10,000, receive $10,000 at the end, and the difference is your interest. That discount structure is the only weird part, and it takes one example to un-weird it.

Terms come in 4, 8, 13, 17, 26, and 52 weeks. The 4-week and 8-week bills are your savings-account substitutes; the 26-week and 52-week are your rate-lock tools.

The math, with one real-feeling example

Suppose a 26-week (half-year) bill is yielding about 4% annualized. On a $10,000 face value, you’d expect to pay roughly $9,804 today and receive $10,000 at maturity — about $196 of interest for six months. If the yield were 4% on a 13-week bill instead, the same logic gives you roughly $98 for the quarter. Nothing else happens: no statements with interest line items, no monthly credits. One price in, one payment out.

(Those are approximate figures — the exact price comes out of the Treasury’s auction, and actual yields float with the market. The point is the shape of the math, and you can check the final numbers on your confirmation screen before the money leaves.)

The Part Nobody Told You About: State Taxes

Here’s the detail that makes T-bills genuinely different from a HYSA, and it’s the first line of my own mental spreadsheet now: T-bill interest is exempt from state and local income tax. You still owe federal tax on it, but your state gets nothing.

Savings account interest, by contrast, is fully taxable everywhere your state taxes income. So the two yields aren’t directly comparable — you have to compare the T-bill’s yield against the HYSA’s yield after state tax. A quick example: if you pay 5% state income tax, a HYSA yielding 4.00% nets you about 3.80% after state tax (4.00% × 0.95), while a T-bill yielding 4.00% still nets the full 4.00% (minus federal tax on both). In a zero-income-tax state like Texas or Florida, the gap vanishes. In California or New York, it’s real money every year on a meaningful cash balance.

That’s the honest shape of it: the higher your state tax rate, the more attractive the bill. Federal tax applies to both, so the comparison is between “yield minus state tax” and “yield.”

How You Actually Buy One

Two routes, and both are more mundane than they sound.

TreasuryDirect. The government’s own portal. You open an account, link your bank, and buy bills at auction. Minimum purchase is $100. Auctions happen on a set schedule (4-week bills, for instance, are issued weekly), and you can schedule purchases in advance so new bills roll automatically as old ones mature. It’s clunky-looking — the interface feels like a government website from another decade, because it is one — but it works, and it costs you nothing in fees.

Your brokerage. Most major brokerages let you buy T-bills on the secondary market or bid at auction through them. This route is nicer if you want the bills to sit alongside your other holdings, and secondary-market purchasing lets you buy mid-cycle instead of waiting for the next auction. Minimums are usually $1,000.

The first purchase feels intimidating for about eleven minutes. Then it feels like paying a bill: pick the term, place the order, see the discount price, done. The hard part is not the mechanics — it’s remembering that the number you see on screen isn’t the price, it’s the face value, and the price is the slightly smaller number underneath.

Laddering T-Bills the Way You’d Ladder CDs

The same stagger-maturity logic from CD laddering applies directly. A common pattern: split your cash into 4-week bills bought every week, so a quarter of the stack matures every week. Or ladder 4/8/13/26-week rungs for the same effect with fewer transactions. When a bill matures, the money appears back in your account; you either spend it (if that was the plan) or reinvest at the new yield.

Compared to a CD ladder, T-bills give you shorter available terms, a state-tax advantage, and no penalty for selling early — because you don’t sell, you just let the bill mature, or if you truly need out you can sell on the secondary market at market price rather than eating a fixed “months of interest” penalty. That’s a structural difference worth understanding if you’re the kind of person who might break the rung: CD penalties are contractually certain, T-bill early exits carry price risk instead. Neither is dangerous for small amounts, but the difference matters when rates move fast.

When I’d Still Use the Boring Savings Account

I keep coming back to this because the honest answer isn’t “T-bills always win.” Several situations where I wouldn’t bother:

• Small balances. The state-tax edge on $5,000 in a 5% state is worth about $10 a year (4% of $5,000 is $200; 5% of that is $10). If a brokerage account adds any friction to your life, $10 a year is not payment for it.
• You need money mid-cycle and hate the idea of selling anything. A savings account is a transfer button. A T-bill is a small position you have to unwind. For emergency money specifically — the money I keep boring on purpose — the transfer button is a feature, not a compromise.
• Your state has no income tax. Then the main T-bill advantage evaporates, and you’re comparing nearly identical yields and choosing the easier account.
• You’re new to cash management. There’s an order of operations to building a financial base, and auction-based instruments sit at the end of it. Get the buffer sized first with the income-based framework, pick an account type (HYSA comparison here), and only then consider whether the tax optimization is worth your attention.

One more wrinkle: T-bills are cousins of other Treasury products, and if you like the general idea of “government-backed savings instruments,” the Series I savings bond is the inflation-protected relative — different purchase limits, a one-year lock, and a different job entirely. I cover it in the Series I bond guide.

The Decision Checklist

1. Is the money emergency money or dated money? Emergency → simple account. Dated → T-bill or CD.
2. Does your state tax interest? If not, the T-bill edge is mostly gone. If yes, quantify it: (state rate) × (HYSA yield) × (balance) is roughly what you’re chasing.
3. Is the balance big enough to matter? Below roughly $10,000, the after-tax edge is usually under $40/year. Above $25,000 it starts being genuinely worth an afternoon.
4. Do you have a brokerage or are you willing to use TreasuryDirect? If neither feels comfortable this year, that’s a fine answer. The savings account isn’t a mistake; it’s just the simpler tool.

I’m not a financial advisor and none of this is financial advice — it’s the mechanics laid out so you can price the tradeoff for your own state and balance.

One Step This Week

If you already have a brokerage account, pull up the Treasury ladder screen and look at what a 13-week and a 26-week bill are yielding today. Compare the 26-week yield to your savings account’s APY minus your state tax rate. If the bill wins by a meaningful margin and you have a chunk of dated cash, put one rung in — the smallest amount you’d be comfortable with — and let the first maturity teach you how the rollover feels. Everything after the first one is copy-paste.