Treasury Bonds and I Bonds Explained: Different Tools for Your Savings

Two federal investments with different jobs

Treasury bonds and Series I savings bonds are both obligations of the U.S. government, but they are not interchangeable. Marketable Treasury bonds can be bought and sold in the securities market. I bonds are nonmarketable savings bonds designed to help protect savings against inflation. Their purchase rules, interest calculations, and access restrictions differ in ways that matter for household planning.

People sometimes use Treasury bond as shorthand for every Treasury security. Technically, Treasury bills have short maturities, notes cover intermediate maturities, and Treasury bonds are issued with twenty-year or thirty-year terms. Treasury Inflation-Protected Securities, or TIPS, are a separate marketable category with inflation adjustments to principal. Knowing the actual product name helps avoid mistakes.

Start with the purpose of the money rather than the most attractive advertised rate. A security suitable for long-term income may be unsuitable for a repair bill next month. Federal backing addresses payment risk, but it does not remove market-price changes, inflation exposure, access restrictions, or the possibility that another investment would better match your needs.

How marketable Treasury bonds work

A conventional Treasury bond pays a fixed coupon every six months and returns its face value at maturity. The coupon rate is set when the bond is issued. If you purchase it later in the secondary market, the price may be above or below face value. Your yield therefore may differ from the coupon printed in the bond's description.

For example, a bond with a $1,000 face value and a hypothetical 4% coupon pays $40 annually, generally in two installments. Paying more than $1,000 lowers the yield relative to the coupon, while paying less raises it, with the maturity payment also affecting the calculation. Compare yield to maturity rather than coupon rates alone when evaluating bonds with different prices.

You can purchase marketable Treasuries through TreasuryDirect at auction or through a brokerage that offers them. Brokerage services, secondary-market pricing, and transaction costs vary. A Treasury held in TreasuryDirect generally must be transferred to a broker or bank before a secondary-market sale, so the holding location affects convenience if you might need to sell early.

Why a safe payment can have a changing price

When market interest rates rise, the price of an existing fixed-rate bond generally falls. Buyers can obtain higher rates on newer securities, so the older bond becomes less attractive unless its price adjusts. When rates fall, the reverse generally occurs. Long-maturity bonds tend to have larger price swings than otherwise comparable shorter-term securities.

Holding a Treasury to maturity avoids having to accept an interim market price for its final principal payment. It does not guarantee that its fixed payments will maintain purchasing power. If inflation runs higher than expected, the dollars received can buy less. It also does not eliminate opportunity cost if newer investments offer better rates.

A Treasury bond fund is different from an individual bond held to maturity. The fund continuously owns a portfolio, and its share price changes with market conditions. It does not promise to return your purchase amount on a particular date. Before using either product for a scheduled expense, consider whether its cash flows actually match that expense.

How I bond interest is calculated

An I bond earns a composite rate based on a fixed rate and an inflation component. The fixed rate is established when you purchase the bond and stays with it for its interest-earning life. The inflation component changes based on the Consumer Price Index for All Urban Consumers, using the Treasury's published calculation rules.

The Treasury announces new rate information in May and November. Your bond's rate resets on its own six-month schedule based on its issue month, not necessarily on the announcement date. Two people checking their accounts on the same day may therefore see different rates. The composite rate also uses a formula rather than simple addition of the two components.

Interest accrues monthly and compounds semiannually. I bonds can earn interest for up to thirty years, and their composite rate cannot fall below zero. Nevertheless, they are not a promise of a permanently high return. Check the current figure for purchase rates, and distinguish the permanent fixed component from the temporary inflation component before buying.

Access restrictions and purchase limits

I bonds cannot generally be redeemed during their first twelve months. If you redeem before five years, you give up the most recent three months of interest. After five years, that interest penalty no longer applies. These rules make a newly purchased I bond unsuitable for money that might be needed immediately for an emergency.

Electronic I bonds are purchased through TreasuryDirect, and annual purchase limits apply by registration and taxpayer identification rules. Gift purchases and trusts can introduce additional requirements, so do not assume that opening more accounts creates unlimited buying capacity. Check the current figure for the purchase limit and review the Treasury's rules before making a large allocation.

Unlike marketable Treasury bonds, I bonds cannot be sold to another investor on an exchange. You redeem them with the Treasury under the applicable rules. That means you do not face a daily secondary-market price, but you also cannot bypass the redemption restrictions by selling to someone else when you suddenly need cash.

Federal and state tax treatment

Interest from Treasury securities and I bonds is generally subject to federal income tax but exempt from state and local income taxes. That exemption can matter when comparing Treasuries with bank deposits, particularly in a state with an income tax. A higher advertised bank rate does not necessarily produce a higher after-tax return.

With I bonds, most cash-basis individual owners elect to defer federal reporting of interest until redemption, final maturity, or another taxable disposition, whichever applies first. Reporting interest annually is another option, but consistency rules matter. Deferred taxation does not mean tax-free interest. Keep purchase and ownership records so the eventual tax reporting is accurate.

Qualified taxpayers may exclude some savings-bond interest when the proceeds meet the federal education exclusion requirements. Income limits, ownership rules, age requirements at issuance, and eligible expenses apply. Do not assume every college payment qualifies. Selling a marketable Treasury before maturity can also create a capital gain or loss, separate from ordinary interest, requiring additional tax reporting.

Choosing a useful combination

For immediate reserves, an insured savings account or another appropriately liquid account may be easier to use than either a long Treasury bond or a newly issued I bond. For a known expense in several months, a Treasury bill maturing near the payment date may fit better than a twenty-year bond. Match the instrument to the timeline.

I bonds can serve as a longer-term inflation-conscious savings layer after the lockup is understood and immediate cash needs are covered. Conventional Treasury bonds may suit investors seeking predictable nominal payments over a long horizon. TIPS offer another form of inflation protection, but their market prices and tax treatment introduce considerations that differ from I bonds.

Before buying, write down the earliest date you might need the money, the account where you will hold it, and the applicable tax treatment. Compare the current yield, access rules, and reinvestment choices. The best choice is not necessarily the investment with the highest quoted number; it is the one whose structure supports the purpose of your savings.

Frequently asked questions