I Bonds vs Treasury Bills: Which Is Right for You?

When you have a chunk of cash sitting around and want it to work harder than your savings account, Treasury securities come up a lot. But there are different types, and I Bonds and Treasury bills (T-bills) are two of the most popular. They're both backed by the U.S. government, they're both safe, and they're both way better than letting money rot in a 0.01% savings account. But they work differently, and which one makes sense depends on your situation.

Let me walk you through how each one works, then help you figure out which is right for you.

How I Bonds Work

An I Bond (Series I Savings Bond) is a savings bond issued by the U.S. Treasury that protects you against inflation. Here's the magic: your interest rate has two components.

First, there's a fixed rate. Right now, that's 1.30% and it stays the same for the entire 30-year life of the bond. Then there's an inflation rate that changes every six months (in May and November). It's based on the Consumer Price Index, and it's added on top of your fixed rate.

So if inflation is 3.50% right now, your combined rate would be around 4.80% (1.30% fixed + 3.50% inflation). But here's the key: if inflation drops, your rate drops too. You'll never earn less than the fixed rate, but you also won't lock in a super high rate if inflation cools down.

I Bonds come with restrictions. You have to hold them for at least one year before you can cash them out. If you cash them out within five years, you lose three months of interest as a penalty. After five years, you can cash them anytime penalty-free.

You buy I Bonds directly from TreasuryDirect.gov for as little as $25 (yes, really). You can buy up to $10,000 worth per calendar year online, plus an additional $5,000 if you buy with your tax refund. Paper bonds are no longer sold, but the online-only route is actually pretty convenient.

How Treasury Bills Work

A Treasury bill (T-bill) is a short-term debt security issued by the U.S. Treasury. The shortest maturity is four weeks, and the longest is 52 weeks. You buy them at a discount to face value and get paid the full amount at maturity.

For example, you might buy a $10,000 T-bill for $9,950 and get $10,000 back in six months. That $50 difference is your interest. It sounds weird, but it's straightforward once you get used to it.

T-bills are purchased through TreasuryDirect or through a broker, and they're incredibly liquid. Your money is only locked up for a few weeks to a year. The current yields on T-bills are in the 4-5% range depending on maturity, which is pretty competitive.

One big difference: T-bill interest is subject to federal income tax but not state income tax. I Bond interest is subject to federal tax (but you can defer it until you redeem) and not state tax. Both are advantageous compared to regular savings accounts.

The Head-to-Head Comparison

Liquidity matters. If you think you might need your money in the next year or two, T-bills are better. You can buy a 4-week or 13-week bill and be done with it. I Bonds lock you in for at least a year, and you lose three months of interest if you pull out before five years.

Predictability. T-bills give you an exact return upfront. You know exactly what you'll earn. I Bonds are less predictable because the inflation component changes every six months. That's great if inflation stays high, but it's a headwind if we slip into deflation or low inflation.

Rate environment. Right now, T-bill rates are around 4.5% for a one-year bill. I Bond rates are around 5.27% (as of early 2026), but remember that includes the current inflation adjustment. If inflation drops significantly, your I Bond rate will drop with it. A T-bill locks in your rate regardless of what happens to inflation.

Tax treatment. Both are federal-taxed but state-tax-free, which is a nice perk. I Bonds let you defer federal tax until redemption, which is a slight advantage for tax planning.

Minimum investment. I Bonds: $25. T-bills: $100 through TreasuryDirect. Both are incredibly accessible.

Which One Should You Choose?

Here's my honest take: Use I Bonds if you're saving for something 5+ years away and want inflation protection. They're perfect for a "set it and forget it" approach to medium-term savings. You're not worried about needing the money, and you want your purchasing power protected as inflation fluctuates. They're also great for kids' college funds or other long-horizon goals.

Use T-bills if you want your money sooner or want certainty. You've got a big expense coming in a year. You're nervous about the economy and want a guaranteed rate. You like knowing exactly what you'll earn. Or you're building a "ladder" of T-bills that mature at different times so you have consistent access to cash.

Stack both if you're being strategic. Many people use T-bills for their emergency fund buffer (beyond their liquid emergency fund) and I Bonds for longer-term savings. It diversifies your returns and your maturities.

The Practical Reality

If I had $20,000 to invest today, here's what I'd do: I'd put $10,000 into I Bonds because that's my annual limit and I'm not touching it for five years. Then I'd split the other $10,000 into a ladder of T-bills—maybe a 13-week bill, a 26-week bill, and a 52-week bill. That way I get some inflation protection, some certainty, and access to cash at different points.

Both are safer than the stock market and way better than letting cash languish in a checking account. Start at TreasuryDirect.gov and set up an account. It takes 10 minutes, and you'll be on your way to making your money work smarter.

The best investment is always the one that matches your timeline and risk tolerance. For most people saving for medium-term goals without high risk tolerance, I Bonds and T-bills are the unsung heroes of personal finance.