A Series I savings bond is a US government bond built specifically to keep pace with inflation. Its interest rate is not one number but two combined — a fixed rate locked in for the life of the bond, and an inflation rate that resets every six months based on consumer prices. That structure makes I bonds one of the few mainstream savings vehicles designed to never lose purchasing power, at the cost of some real liquidity restrictions worth understanding before you buy.
What changed in 2026
- The fixed-rate component keeps being set at each May and November announcement, and it varies by cohort — the rate you lock in depends on when you buy, not when you sell.
- The inflation-rate component continues resetting every six months based on the most recent CPI data, so your total rate can rise or fall over the life of the bond.
- TreasuryDirect remains the only purchase channel for electronic I bonds, since brokerages do not offer them.
- The paper-bond option via tax refund remains a separate, smaller allowance, on top of the standard electronic limit.
How the composite rate works
Every I bond earns a composite rate made of two pieces added together (with a small adjustment for how they interact):
- Fixed rate — set when you buy the bond and locked in for its entire life, even 30 years.
- Inflation rate — recalculated every six months from your purchase anniversary, based on the change in the Consumer Price Index.
Example: say the fixed rate at purchase is 1.0% and the semiannual inflation rate works out to an annualized 3.0%. Your composite rate for that six-month period is roughly 4.0%. Six months later, if inflation cools and the new inflation component drops to an annualized 2.0%, your composite rate becomes roughly 3.0% for the next period — your fixed rate never moves, but the inflation half keeps adjusting.
I bonds vs other safe cash options
| Feature |
I Bonds |
T-Bills |
High-yield savings |
| Rate structure |
Fixed + inflation, resets every 6 months |
Fixed discount, locked at purchase |
Variable, bank-set |
| Minimum hold |
12 months, no exceptions |
None — sell anytime on secondary market |
None |
| Early withdrawal cost |
Forfeit last 3 months' interest if under 5 years |
Market price if sold before maturity |
None |
| Annual purchase cap |
Yes, a set dollar limit per person |
No practical cap for most investors |
No cap |
| State/local tax |
Exempt |
Exempt |
Fully taxable |
Buying and cashing out
I bonds are purchased directly at TreasuryDirect.gov, in electronic form, up to the annual per-person limit; a smaller additional paper-bond allowance is available only through your federal tax refund. Once bought, the bond cannot be redeemed at all for the first 12 months. Between one and five years, cashing out forfeits the three most recent months of interest — a real but limited penalty. After five years, you can cash out anytime with no penalty, and the bond keeps earning interest for up to 30 years if you leave it alone.
Common mistakes
Treating I bonds as emergency-fund cash. The 12-month lockup means true short-notice money should sit somewhere fully liquid, like a high-yield savings account or a short T-bill, not in an I bond.
Assuming the rate is fixed for the full term. Only the fixed-rate half is locked in; the inflation half changes every six months, so your effective yield moves over time even though you did nothing.
Missing the purchase-limit cap. The annual electronic limit is per person, per calendar year — a couple can each buy up to their own limit, effectively doubling household capacity, but you cannot exceed your individual cap in one account.
Cashing out right before hitting a rate reset. Since the inflation component recalculates every six months from your purchase date, cashing out a few days early can mean missing an improved rate that was about to apply.
FAQ
Can I lose money on an I bond?
No — the composite rate cannot go below zero, so your balance never declines in nominal terms, though the early-withdrawal interest forfeiture reduces what you would have otherwise earned.
How do I buy I bonds?
Through a TreasuryDirect.gov account, funded from a linked bank account, up to the annual electronic purchase limit per person.
Are I bonds better than T-bills right now?
It depends on the current fixed rate versus current bill yields, and on how long you can lock the money away. Bills offer more flexibility since they can be sold anytime; I bonds offer inflation protection but a mandatory 12-month hold.
Do I owe tax every year on I bond interest?
Generally no — federal tax is deferred until you cash the bond or it reaches final maturity, though you can elect to report interest annually. Interest is exempt from state and local tax either way.
Where to go next
For the shorter-maturity alternative, see treasury bills explained for 2026. For a broader view of where bonds fit in a portfolio, read how to invest in bonds in 2026 and the bond investing guide for 2026.