What are I bonds?

In 2021 and 2022, when inflation hit 8%+, I bonds became a personal finance obsession. Rates briefly hit 9.62% and everyone wanted in. Then inflation cooled, rates normalized, and the conversation moved on. That hype cycle is actually a useful frame — I bonds are genuinely interesting in some circumstances and useless in others, and the crowd tends to discover them at exactly the wrong time.

Series I savings bonds (“I bonds”) are issued directly by the Treasury, adjust with inflation, and carry tax advantages a bank savings account can’t match — with a $10,000-per-person annual cap that keeps them from being useful at any real scale.

Used correctly, they’re a solid piece of an emergency fund or a cash holding for a mid-term goal. Used incorrectly (chasing yield, parking your whole portfolio), they’ll disappoint.

The two-part interest rate

I bonds pay interest every month, compounded semiannually. The rate has two components:

1. Fixed rate — set when you buy, stays the same for the 30-year life of the bond
2. Inflation rate — reset every six months based on CPI-U

Your composite rate combines the two (approximately: fixed + inflation, with a small adjustment). Historical fixed rates have ranged from 0% (most of the 2010s) to 3.6% (late 1990s). The inflation component tracks actual CPI, so I bonds roughly break even with inflation no matter when you buy — that’s their defining feature.

The Treasury announces new rates each May 1 and November 1. Bonds you already own continue to earn interest under the same structure; the fixed rate is locked, the inflation component updates automatically every six months from your purchase date.

The purchase limits that shape everything

Each person can buy:

• $10,000/year in electronic I bonds through TreasuryDirect.gov
• $5,000/year in paper I bonds (only via federal tax refund using Form 8888)

For a married couple, that’s up to $30,000/year total ($10k each electronic + $5k each paper — though the $5k paper limit is per tax return, shared). You can also buy $10k/year per trust entity if you set one up.

This cap is the single biggest constraint. I bonds are too small to be anyone’s main investment vehicle, but they’re a useful parallel slot for cash you’d otherwise hold in a savings account.

Liquidity rules

I bonds are not liquid the way a savings account is:

• First 12 months: cannot redeem at all (unless a federally declared disaster)
• Months 12–59: can redeem, but forfeit the last 3 months of interest
• Year 5+: redeem any time with no penalty
• Year 30: automatic maturity, bond stops earning

The 3-month interest penalty is small when inflation is low, more painful when inflation is high. Most planners treat I bonds as “cash you hope to keep for at least a year” — not emergency-today money.

Tax treatment — the quiet advantage

I bonds have three tax features that make them attractive:

1. Federal taxes can be deferred until you redeem the bond (or it matures at year 30). You can also elect to pay each year as interest accrues, which is rarely useful.
2. State and local tax exempt. Unlike savings accounts, all Treasury interest is free of state income tax.
3. Education exclusion. If you redeem I bonds in a year you pay qualified higher-education expenses, interest may be fully tax-free. Income limits apply and they’re lower than most families expect — verify before counting on this.

For someone in a high-tax state, the state-tax exemption alone often adds 0.3–0.8% effective yield compared to a bank savings account paying the same stated rate. That’s real money.

How to buy them

You open an account at TreasuryDirect.gov. The site feels like a 2003 government portal because it is one, but the mechanics are reliable:

1. Create an account with your SSN and a bank account.
2. Enter the purchase amount and submit.
3. The bond appears in your account on the first business day of the following month, with the prior month’s purchase date locked in.

Timing trick: buy late in the month. Treasury treats your purchase as having been held the entire calendar month, so buying on April 30 vs. May 1 can effectively add a month of interest. Late-month buying plus paying attention to May/November rate announcements is about as much optimization as I bonds reward.

Paper I bonds via tax refund: fill out IRS Form 8888 with your tax return, specifying up to $5,000 to be issued as paper bonds. They’ll arrive by mail a few weeks after the refund is processed.

When I bonds make sense

I bonds fit well as:

• Part of an emergency fund after year one. Keep 3 months of expenses in a liquid high-yield savings account; once you’re above that, I bonds are a reasonable home for additional reserves.
• A planned mid-term expense 1–5 years out. Down payment, wedding, planned sabbatical — I bonds beat a CD for the inflation protection, assuming you can tolerate the 12-month lock-up.
• An inflation hedge in a fixed-income allocation. Useful for retirees whose largest risk is losing purchasing power.
• A kid’s college fund — sometimes, if you qualify for the education exclusion.

When they don’t

I bonds are a poor fit for:

• Long-term retirement savings. The $10k cap makes them too slow to build meaningful balances. Put that money in a 401(k) or IRA first.
• Short-term money you might need in a hurry. The 12-month lock-up is absolute.
• High-tax-bracket investors chasing yield. TIPS, short Treasury bills, and municipal bonds can beat I bonds on after-tax yield in many environments.
• Anyone not willing to deal with TreasuryDirect. The website experience is genuinely bad.

How I bonds compare to the obvious alternatives

Product	Inflation protection	Liquidity	Federal tax	State tax	Limit
High-yield savings	None	Immediate	Yes	Yes	None
Short CD	None	At maturity	Yes	Yes	None
T-Bills (1–6 mo)	Market-driven	At maturity (or secondary market)	Yes	No	None
I Bonds	Direct CPI link	After 12 mo + 3 mo penalty until yr 5	Deferred	No	$10k/yr
TIPS	CPI-linked principal	Via secondary market	Yes	No	None

TIPS and I bonds are the two mainstream inflation-linked Treasury products. I bonds are simpler, harder to hold in large amounts, and give you tax deferral. TIPS are more flexible, tradable, and buyable in any amount. Neither is wrong — they serve different purposes.

Further reading

• Inflation calculator — visualize the purchasing-power drag I bonds are designed to offset
• Emergency Fund calculator — size your emergency fund, then consider I bonds for the “tier 2” layer
• Understanding inflation — why CPI-linked products exist
• TreasuryDirect: Series I Savings Bonds — official rates and rules