I Bonds vs TIPS: Which Inflation-Protected Investment Makes More Sense Right Now?

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TIPS now pay more than double the fixed rate of I bonds, 2.2% versus 1.1%. That spread has yanked the inflation‑hedging conversation wide open. The composite rate on I bonds sits at a respectable 3.98% according to the U.S. Treasury’s May 2025 announcement, but when you strip away inflation, the real‑return gap is the widest it has been in over two decades. Deciding between I bonds vs TIPS in August 2025 means choosing between a tax‑deferred, zero‑risk buffer and a tradable security with a substantially higher guaranteed real yield.

The stakes changed quietly. I bonds were the darling of 2022 when inflation spiked and safe yields were scarce. Now, with TIPS real yields above 2.2% and I bonds offering only a 1.10% fixed component per the Treasury’s current rate schedule, the math has flipped. Every percentage point of guaranteed real return compounds for years, and the difference can rewrite the end of a retirement plan or a down‑payment timeline.

The analysis that follows compares the two instruments across the only dimensions that count, yield, taxes, liquidity, purchase caps, and scenario outcomes, using publicly available Treasury data.

Same CPI Index, Different Engine: How I Bonds and TIPS Actually Work

I bonds and Treasury Inflation‑Protected Securities are the only two inflation‑indexed debt instruments issued by the U.S. government, and both use the Consumer Price Index for all Urban Consumers (CPI‑U) to adjust returns. The mechanics, however, fork after page one.

An I bond earns a composite rate made of a fixed rate, set at purchase, plus a variable semiannual inflation rate. The fixed rate stays for the bond’s 30‑year life. TIPS pay a coupon on an inflation‑adjusted principal; that principal rises with CPI‑U. If deflation hits, TIPS principal shrinks, but at maturity the Treasury pays the higher of the adjusted principal or the original face value. I bonds never go backwards: the composite rate floor is zero, meaning the bond’s value can only rise or stay flat.

The most immediate takeaway: both respond to the same CPI‑U data, but TIPS embed a larger guaranteed real return right now. The I bond’s smaller fixed rate gets compensated by its tax‑deferral feature and the fact that its composite never dips below zero, a trait that shows up only when the economic weather turns ugly.

August 2025 Yields: A 1.1‑Point Gap That Hasn’t Been This Wide in Over 20 Years

The I bond composite rate for bonds issued from May through October 2025 is 3.98%, composed of a 1.10% fixed rate and a 2.88% annualized semiannual inflation rate, as published by the U.S. Treasury Fiscal Service. That is a solid nominal return for a risk‑free instrument, but the headline hides the real story: the fixed portion is what you get after inflation zeroes out, and 1.10% is modest.

The 10‑year TIPS real yield sits near 2.2%, according to the Federal Reserve’s H.15 interest rate release. Even the 5‑year TIPS real yield topped 1.9% that month. Long‑term, a 30‑year TIPS auction in early 2025 produced a real yield of 2.65%, the highest in nearly a quarter century. Those numbers mean a TIPS investor locks in an after‑inflation return roughly twice the I bond’s fixed component for the same government guarantee.

Treasury guarantees matter. The credit risk is identical. The difference boils down to how the return is packaged. The I bond pays the inflation portion each year within the composite while promising only a 1.1% real floor. TIPS guarantee a 2.2% real yield on top of inflation, paid through coupons and principal accretion. For a $10,000 investment held one year with 2.88% inflation, the same annualized rate embedded in the current I bond, a TIPS would generate about 5.08% nominal ($508) versus the I bond’s $398. The $110 difference comes straight from the real‑yield advantage.

Liquidity, Purchase Caps, and Penalties

I bonds are not marketable securities. You can’t sell them to another investor. Redeeming early means losing the last three months of interest if you cash out before the five‑year mark, and you must wait a full year before accessing any money. TIPS trade in one of the deepest markets on earth and can be sold the day after purchase, no penalty, at the prevailing market price.

The purchase cap adds another hard limit. An individual Social Security Number may buy only $10,000 in electronic I bonds per calendar year. That ceiling walls off anyone trying to steer more than a few thousand dollars of annual savings into inflation protection. TIPS have no such limit. An investor can buy millions of dollars’ worth of TIPS through a brokerage account, or opt for a low‑cost ETF like VTIP for daily liquidity and zero dollar minimums. For large portfolios, the choice isn’t I bonds vs TIPS, it’s TIPS or nothing.

One underappreciated caveat: TIPS market prices move with real interest rates. If you buy a 10‑year TIPS and real yields rise 50 basis points the following month, the market value of your holding drops. For buy‑and‑hold investors that fluctuation is irrelevant, but anyone who might need the money before maturity faces genuine price risk. I bonds sidestep this entirely because they are non‑marketable and always redeemable at face value plus accrued interest. That price stability is not a small thing for investors who cannot afford to sell at the wrong moment.

This distinction drives the practical deployment. I bonds function as a high‑floor savings vehicle. TIPS are a yield instrument. If your time horizon is under one year, I bonds are off the table entirely. If it’s between one and five years, the penalty tilts the math further; a $10,000 I bond redeemed at 48 months effectively sacrifices three months of 3.98%, roughly $100, while a TIPS fund can be liquidated instantly. For holding periods beyond five years, the liquidity gap narrows, but the cap remains.

Tax Deferral vs. Phantom Income

Both instruments escape state and local taxation, a benefit even the highest‑yielding CDs can’t match. At the federal level, the treatment diverges sharply: I bond interest is tax‑deferred until redemption (or maturity), while TIPS produce taxable income every year on both the coupon and the CPI‑driven increase in principal, income you don’t pocket until you sell. That “phantom income” hits even if you reinvest dividends. The Federal Reserve’s interest rate data makes the yield comparison straightforward, but the after‑tax outcome is where the two instruments diverge most sharply for taxable investors.

Deferral tilts the field. A taxpayer in the 22% federal bracket who buys a $10,000 I bond at 3.98% and holds for five years earns about $2,147 in interest, all taxed in year five: $472 due, net after‑tax redemption $11,675. A TIPS with 2.2% real yield plus 2.88% inflation yields roughly 5.08% nominal, but the annual tax drag, paying 22% each year on accrued interest and inflation adjustments, reduces the cumulative after‑tax terminal value. In many taxable scenarios, the deferral makes I bonds competitive despite the lower real rate. Inside an IRA or 401(k), however, TIPS handily win with a 2.2% real yield free of tax friction.

It’s also worth being direct about who TIPS are a poor fit for. Investors holding TIPS in a taxable account who are in a high marginal bracket can find themselves writing a tax check each April for income that exists only on paper. That annual cash outflow reduces compounding and can make the after‑tax real return on TIPS look much closer to the I bond’s than the pre‑tax numbers suggest. High‑bracket taxable investors who cannot shelter TIPS inside a retirement account should run the numbers carefully before assuming the higher real yield wins automatically.

Who Should Own What

For a young professional investing for the first time, the I bond is the easiest inflation hedge to understand and the safest place to park emergency savings. Five thousand or ten thousand dollars in I bonds means real purchasing power preservation without market noise. The TreasuryDirect interface is clunky, but the bonds sit quietly, and the tax bill waits until you cash them.

For a retiree with a $600,000 portfolio, the $10,000 annual I bond purchase cap is an obstacle, not a solution. Allocating meaningful capital requires TIPS, ideally inside a retirement account where the phantom income is moot. An ETF like VTIP provides a 0.04% expense ratio and virtually unlimited capacity. The choice scales with account size: under $10,000, I bonds; over $100,000, TIPS or a low‑cost fund.

According to NerdWallet’s analysis of I bonds, parking cash in I bonds earmarked for a near‑term goal like a down payment aligns well with the instrument’s design: a known future expense, a one‑to‑five‑year window, and a need for principal certainty. For anything larger or longer, TIPS take the stage.

Performance Under Three Inflation Paths

In every scenario where inflation stays positive, TIPS outperform I bonds by roughly 1.1 percentage points annually before taxes, the exact difference between the 2.2% real yield and the 1.1% fixed rate. That spread is a structural advantage that only vanishes when the economy tips into outright deflation for an extended period.

The deflation case is where the zero floor puts a hard bottom under your cash. If prices fall 3% in a year, TIPS principal would decline by 3%, pulling the nominal return into negative territory even after the real yield is added. The I bond composite rate would compute to a negative number, and then be reset to zero by Treasury. You earn nothing, but you lose nothing. A retirement account that must generate cash flow in a deflationary shock might prefer the I bond cushion; an accumulator with decades ahead can absorb the temporary TIPS dip knowing the bond matures at face value.

This isn’t theoretical. While the U.S. hasn’t experienced a prolonged deflation since the 1930s, the TIPS principal reduction during the 2008–2009 financial crisis reminded holders that CPI can go down, and TIPS values fell in tandem. I bonds, invisible to markets, simply idled at zero.

Right Now: Where Each Instrument Wins

A tax‑deferred account loaded with TIPS gives you a 2.2% real yield, more than double the I bond’s 1.10% fixed rate as published by the Treasury Fiscal Service. That’s the cold math. If you have an IRA or 401(k) with an allocation to bonds, shifting a slice into a low‑cost TIPS ETF or buying individual TIPS at auction is the highest‑expected‑return inflation hedge available without taking credit risk. Tax‑filing season becomes simpler, too, because the annual 1099 from a brokerage captures what you need, with no phantom income surprises if the TIPS are inside a retirement wrapper.

Yet the I bond hasn’t lost its seat at the table. Its composite rate of 3.98% is competitive with high‑yield savings, and the tax deferral plus state tax exemption produce an after‑tax return that, for many middle‑bracket taxpayers held 3 to 7 years, ends up close to a taxable TIPS. The $10,000 limit per TreasuryDirect’s purchase rules is a genuine constraint, but for building a no‑volatility emergency tier, it’s sufficient. The strategy: max out I bonds for your safety net, then fill any remaining inflation‑protection allocation with TIPS in tax‑advantaged accounts.

What This Means for You

The real‑yield gap is a signal worth acting on. For investors who can hold TIPS in a retirement account or who need unlimited scale, the math is decisive. For everyone else, the I bond remains a unique tax‑deferred, no‑loss wrapper that no other security replicates. Translate the findings into these five steps:

1. Check your tax‑deferred space first. If you have a 401(k) or IRA with room to add bonds, buy TIPS, individually or through a low‑cost ETF, and lock in a 2.2% real yield without tax drag.
2. Max out your I bond allowance for cash you might need in 1–5 years. The $10,000 limit per person makes it a built‑in emergency‑fund builder. Hold at least 12 months and aim for five years to dodge the interest penalty.
3. Don’t buy I bonds in December unless you’ve already used the current fixed rate window. The fixed rate can change every May and November; if you wait and the fixed portion drops, you lose it.
4. In a taxable account, model the after‑tax outcome. If your federal rate is above 24% and you’re in a high‑tax state, the I bond deferral often overcomes the lower real rate over a 3‑ to 10‑year horizon.
5. Protect the tail with I bonds if deflation worries you. The zero floor is an insurance policy that costs you about 1.1 percentage points of real return each year, a premium worth paying if a nominal loss would force you to sell other assets at the wrong time.

Frequently Asked Questions

Are I bonds or TIPS better for a one‑year investment horizon?

I bonds cannot be redeemed within the first 12 months, so they are unusable for a one‑year window. TIPS can be sold anytime, but price volatility may cause a small loss. A one‑year Treasury bill often makes more sense for such a short duration.

How are I bonds and TIPS taxed differently?

Both are exempt from state and local income taxes. I bonds defer all federal tax until redemption; TIPS generate taxable income each year on both coupon payments and inflation adjustments, even if that income isn’t received in cash.

Can I buy I bonds in an IRA?

No. I bonds cannot be held in any tax‑advantaged retirement account. TIPS can be purchased directly in IRAs or through mutual funds and ETFs.

What is the current I bond rate right now?

Bonds issued from May through October 2025 carry a composite rate of 3.98%, consisting of a fixed rate of 1.10% and a semiannual inflation rate of 1.44% (2.88% annualized), per the Treasury’s official rate announcement.

Do TIPS lose value if inflation falls?

Yes, the principal adjusts downward in line with CPI‑U. However, at maturity the Treasury will pay the original face value or the inflation‑adjusted principal, whichever is higher. In the interim, the market value can decline.

Is there a maximum amount of TIPS I can buy?

No. Treasury sets a competitive auction limit but individuals can purchase any amount through noncompetitive bids or the secondary market. There is no annual cap like the $10,000 I bond limit.

Which one hurts less when the Fed raises rates?

I bonds are non‑marketable so rate changes don’t affect their redemption value. TIPS market prices decline when real rates rise, though for a buy‑and‑hold investor the real yield at purchase remains intact.

Can I sell TIPS before maturity without penalty?

Yes. TIPS trade on the secondary market. You can sell at any time with no penalty, but you may receive more or less than the adjusted principal depending on prevailing interest rates.

Why not just use a TIPS ETF instead of individual bonds?

An ETF like VTIP provides instant diversification, daily liquidity, and no minimum purchase, ideal for investors who want inflation protection without managing individual bonds. The trade‑off is a small expense ratio and no guaranteed maturity payout.