I bonds vs TIPS: which inflation-protected bond is better?

Ask the United States Treasury to protect your savings from inflation and it will hand you two different products. The Series I savings bond and Treasury Inflation-Protected Securities — TIPS, in market shorthand — are both engineered so that rising prices cannot quietly eat your money, and both lean on the same official inflation gauge to do it. That is roughly where the resemblance ends. One is a savings product you cannot trade, with a hard annual cap and a value that only moves up. The other is a market bond with no cap at all, a richer real yield, and a price that can fall at exactly the wrong moment.

This piece is the head-to-head between those two structures. For the anatomy of one instrument on its own, the full mechanics of Series I savings bonds cover the rate formula and the redemption fine print, while the matchup of the I bond against its fixed-rate sibling, the Series EE bond settles a different question entirely. Here the decision turns on how much you are investing, how long the money can sit, and what kind of account it will live in.

Both protect purchasing power, but differently. A Series I savings bond pays a 4.26% composite rate, caps you at $10,000 a year, and never loses value — you just can’t touch it for 12 months. TIPS yield about 2.19% real with no purchase cap, but their price swings if you sell before maturity.

Two ways to chain a dollar to the same index

Both instruments anchor to the Consumer Price Index for All Urban Consumers, the CPI-U, the government’s headline measure of inflation. Everything around that anchor is different.

The Series I savings bond is a savings product, not a market security. You buy it from the Treasury and you redeem it with the Treasury; it never trades, so it has no market price that can fall. Its interest comes from a composite rate: a fixed rate locked for the bond’s entire life, plus an inflation rate recalculated every six months from the CPI-U. For bonds issued from May through October 2026, the fixed rate is 0.90% and the semiannual inflation rate is 1.67%, which combine into a 4.26% composite rate. The wrapper has teeth, though. You cannot redeem at all during the first 12 months, cashing out before five years forfeits the last three months of interest, and electronic purchases are capped at $10,000 per person per calendar year. Left alone, the bond keeps earning for up to 30 years.

Treasury Inflation-Protected Securities approach the same goal from the opposite direction. A TIPS is an ordinary marketable Treasury bond — issued at auction in 5-, 10-, and 30-year terms, with a $100 minimum on TreasuryDirect — whose principal is adjusted with the CPI-U. Inflation pushes the principal up, and the bond’s fixed coupon is paid twice a year on that adjusted principal, so the dollar interest grows with prices as well. At maturity you receive the greater of the adjusted principal or the original face value — a deflation floor, so a buy-and-hold investor cannot be handed back less than par. And there is no ceiling worth mentioning: beyond TreasuryDirect auctions, you can buy TIPS through any brokerage on the secondary market, or wrap the exposure in TIPS mutual funds and exchange-traded funds.

The real-yield gap: 0.90% guaranteed versus 2.19% with strings

Strip inflation out of each instrument and what remains is the real return — the part you earn above rising prices — and here the comparison stops being close. The I bond’s real return is its fixed rate: 0.90% for May–October 2026 purchases, locked for the life of the bond and delivered with zero price risk. A 10-year TIPS pays considerably more. At the Treasury’s auction in late May 2026, the 10-year TIPS cleared at a real yield of 2.169%, and the market yield on the 10-year stood near 2.19% as of June 9, 2026. That is a gap of roughly 1.3 percentage points per year, above inflation, for a decade.

So why would anyone accept the I bond’s 0.90%? Because the TIPS yield carries a condition the I bond never imposes: you only lock in that 2.19% if you hold the bond to maturity. In the meantime the TIPS trades, and when real yields rise, the prices of existing TIPS fall — an investor who needs the money in year three of a ten-year bond may have to sell at a loss, inflation protection notwithstanding. The I bond cannot do that to you. Its redemption value only ratchets upward, and the worst the Treasury can take from an early exit is that three-month interest clip. That extra yield is the market’s payment for carrying the price risk yourself.

The side-by-side

Side by side, the trade-offs sort into a clean grid.

	Series I savings bond	TIPS
Rate today	4.26% composite (0.90% fixed + 1.67% semiannual inflation), May–Oct 2026 issues	~2.19% real yield on the 10-year (Jun 9, 2026); 5-, 10-, and 30-year terms
Purchase limit	$10,000 per person per year, electronic	No practical cap; $100 minimum at auction
Liquidity	Locked the first 12 months; 3-month interest penalty before year 5	Tradable any business day on the secondary market
Price risk	None — redemption value never declines	Prices fall when real yields rise; full protection only at maturity
Taxes	Federal tax deferred until redemption; exempt from state and local tax	Inflation adjustment taxed yearly as it accrues; exempt from state and local tax
Where to buy	TreasuryDirect only	TreasuryDirect auctions, any brokerage, or TIPS funds and ETFs

The buying mechanics overlap at the government’s own storefront — the step-by-step guide to opening and using a TreasuryDirect account covers both purchase flows — but only TIPS exist beyond it.

Taxes: quiet deferral versus phantom income

The tax row in that table deserves more than a cell, because it should decide where you hold each instrument. Both carry the Treasury family perk: interest is exempt from state and local income tax, a real edge in high-tax states. After that they diverge. I bond interest is federally deferred — you owe nothing until you redeem the bond or it stops earning at year 30 — so the interest compounds untaxed and you choose the year the tax bill lands. That makes the I bond a naturally good citizen of an ordinary taxable account.

TIPS behave worse there. The inflation adjustment added to a TIPS principal each year is taxable as interest income in the year it accrues, even though you do not receive that money until the bond matures or you sell. Investors call it phantom income: real tax on cash you have not collected. The standard fix is placement — hold TIPS inside a tax-advantaged account such as an IRA or 401(k), where the annual adjustment is a non-event, and let the I bond do its slow, deferred work on the taxable side.

How to decide

Put the pieces together and the decision usually makes itself. If the amount fits under $10,000 a year, the money sits in a taxable account, and you want inflation protection that can never show you a loss, buy the I bond — and accept the 12-month lockup and the slimmer 0.90% real rate as the price of total calm. If the sum is bigger than the cap, the money lives in an IRA or 401(k), or you can genuinely commit to holding to maturity, buy TIPS and collect the extra 1.3 points of real yield for price risk you have arranged never to feel. The two also combine well: fill the I bond allowance each year and route the overflow into TIPS.

And if the honest answer is that you might need this cash within a year, neither instrument is built for you. The I bond is sealed shut for 12 months, and a TIPS sold early at the wrong moment can come back smaller than it went in. Short-horizon money belongs with the boring trio of Treasury bills, high-yield savings accounts, and money market funds. Inflation protection is for money that can sit still long enough to collect it.

Sources

• TreasuryDirect — I bonds — structure of the Series I savings bond: 12-month redemption lock, three-month interest penalty before five years, 30-year earning life, $10,000 annual electronic purchase limit, and federal tax deferral with state and local exemption.
• TreasuryDirect — I bonds interest rates — the 4.26% composite rate for May–October 2026 issues, decomposed into the 0.90% fixed rate and the 1.67% semiannual inflation rate.
• TreasuryDirect — Treasury Inflation-Protected Securities (TIPS) — CPI-U principal adjustment, coupon paid on the adjusted principal, 5-, 10-, and 30-year terms, $100 auction minimum, and the greater-of-adjusted-principal-or-par payout at maturity.
• FRED — 10-Year Treasury Inflation-Indexed Security, Constant Maturity (DFII10) — market real yield on the 10-year TIPS, around 2.19% as of June 9, 2026.
• Tipswatch — 10-year TIPS auction gets real yield of 2.169% — result of the late-May 2026 auction of the 10-year TIPS.

Rates shown are the Treasury’s published figures for May–October 2026 I bond issues and market levels as of early June 2026; the I bond composite resets every six months and TIPS yields move daily, so confirm the current numbers before you buy.