Both I-bonds and TIPS (Treasury Inflation-Protected Securities) are issued by the U.S. Treasury, both are designed to protect against inflation, and both are frequently confused with each other by investors who know they want something that keeps up with rising prices. They work very differently in practice. And for a 55-year-old investor in the 22% federal tax bracket — someone with a decade or more before retirement who’s thinking seriously about inflation risk — the choice between them depends on specific factors that most generic comparisons skip entirely.
The short answer: I-bonds are better for shorter-term inflation protection and emergency-adjacent savings. TIPS are better for long-term inflation hedging inside a tax-advantaged account. Most 55-year-olds should consider owning both, in different parts of their portfolio, for different purposes. But if you’re only going to own one, the account you’d put it in matters more than most people realize.
How I-Bonds Actually Work
I-bonds are savings bonds purchased directly through TreasuryDirect.gov. The interest rate has two components: a fixed rate (set at issue and locked for the life of the bond) and an inflation component (the CPI-U rate, adjusted every six months). The combined rate resets each May 1 and November 1. When inflation is high, I-bond rates are high. When inflation cools, the rate drops accordingly.
Key constraints:
- Purchase limit of $10,000 per person per year through TreasuryDirect (plus $5,000 additional via tax refund purchase)
- Must hold for at least 12 months before redemption
- If redeemed within 5 years of purchase, you forfeit the last 3 months of interest
- Interest is federal-taxable but state and local tax-exempt
- Interest is deferred until redemption — you don’t pay tax until you sell
The tax-deferral feature is genuinely valuable. You earn interest for years, potentially decades, without paying a dollar of federal tax until you redeem. If you redeem in a low-income year — say, early retirement before Social Security kicks in — you might owe substantially less tax on that accumulated interest than you would have paid annually.
How TIPS Actually Work
TIPS are marketable Treasury securities — you can buy them at auction through TreasuryDirect or buy a TIPS mutual fund or ETF (like Vanguard’s VIPSX or iShares TIP ETF) in a brokerage account. The principal adjusts with inflation: when CPI rises, the face value of your TIPS increases, and your interest payment (paid at a fixed coupon rate on the adjusted principal) also increases.
This inflation-principal adjustment is where TIPS get complicated for taxable accounts. Every year, the IRS requires you to pay federal income tax on the inflation adjustment to your principal — even though you haven’t actually received that money yet. It’s called "phantom income." If your TIPS principal increases by $500 due to inflation this year, you owe tax on that $500 now, not when you sell.
This makes TIPS in a taxable account a poor choice for most investors. The annual phantom income tax drag is a real cost that erodes the inflation protection you’re paying for.
TIPS in a tax-advantaged account — a traditional IRA, Roth IRA, or 401(k) — completely avoid this problem. Inside a tax-deferred or tax-free wrapper, the phantom income issue disappears. The general rule of thumb on asset placement is that tax-inefficient assets belong in tax-advantaged accounts — and TIPS are among the clearest examples of this principle in practice.
The Head-to-Head Comparison for a 55-Year-Old at 22%
At 55 in the 22% bracket, you have roughly 10-20 years of horizon, probably a mix of taxable and tax-advantaged accounts, and a legitimate concern about inflation eroding your purchasing power in retirement. Even modest inflation over 20 years meaningfully reduces what your savings can buy — this isn’t a theoretical concern.
Here’s how I-bonds and TIPS stack up across the key dimensions that matter at your stage:
Purchase limits: I-bonds cap at $10,000/year per person ($20,000 for a married couple). TIPS have no practical limit — you can buy as much as you want through a TIPS fund or at auction. If you want meaningful inflation protection across a large portfolio, TIPS can scale; I-bonds can’t.
Tax treatment in a taxable account: I-bonds win clearly. Tax-deferred until redemption, state and local tax exempt. TIPS in taxable accounts generate phantom income annually — you pay federal tax on principal adjustments you haven’t actually pocketed. For a 22% bracket investor with TIPS in a taxable brokerage account, the phantom income tax meaningfully reduces the effective yield.
Tax treatment in a tax-advantaged account: TIPS win. Inside an IRA or 401(k), phantom income is irrelevant. TIPS can serve as the inflation-linked fixed income anchor of a retirement portfolio without the taxable-account headache.
Liquidity: I-bonds are liquid after 12 months (with the 3-month interest penalty before 5 years). TIPS ETFs are liquid any trading day. A TIPS fund at Vanguard or Fidelity can be sold in minutes; a TreasuryDirect I-bond takes longer to process.
Rate certainty vs. market price: I-bonds have no market price risk — you can’t lose principal, and the rate adjusts with inflation regardless of interest rate movements. TIPS, when bought as individual securities or ETFs, have market prices that move inversely with real interest rates. When real yields rise, TIPS prices fall. A TIPS fund can lose money in the short run even when inflation is rising if real rates are rising faster. I-bonds don’t carry this risk.
Duration and flexibility: I-bonds mature in 30 years but can be redeemed anytime after 12 months. TIPS come in 5, 10, and 30-year maturities; TIPS funds hold a rolling mix of maturities. For a 55-year-old, a 10-year TIPS directly matches a common retirement planning horizon.
My Take: The Right Answer Is Probably Both
I started thinking seriously about inflation protection in my late 50s — partly from watching the NWS analyze atmospheric conditions that always seemed to shift direction when you least expected it, and partly from watching my own parents’ fixed pension income get quietly eroded through their 70s and 80s. Inflation isn’t dramatic. It’s slow and invisible until it isn’t.
For most 55-year-olds in the 22% bracket, I’d structure it this way:
- I-bonds in a taxable account: Max your $10,000/year purchase ($20,000 if married) as a safe, inflation-linked alternative to cash or a high-yield savings account for your non-emergency savings tier. Tax-deferred, state-tax-exempt, no market price risk. Think of these as replacing part of what you’d otherwise keep in a high-yield savings account or short-term CD.
- TIPS in your IRA or 401(k): If your plan offers a TIPS fund (many do — Vanguard Inflation-Protected Securities Fund, Fidelity Inflation-Protected Bond Index), allocate part of your fixed income allocation there. For a 55-year-old with a 10-15 year horizon, a 10-20% TIPS allocation within the bond portion of the portfolio is a reasonable starting point. This is the place where TIPS’ phantom income problem is eliminated entirely.
What I’d specifically avoid: TIPS in a taxable brokerage account, where the annual phantom income tax makes them structurally inferior to I-bonds for almost any investor in a meaningful tax bracket.
The Rate Environment Question
I-bond and TIPS rates both move with inflation, but differently. I-bond composite rates are backward-looking — they reflect CPI changes over the previous six months. TIPS real yields are market-determined — they reflect what investors currently demand above inflation to hold Treasury bonds.
When real yields are low or negative (as they were for extended periods), I-bonds often offer a better yield than comparable TIPS on an after-tax basis. When real yields are high (as they’ve been more recently), TIPS at auction become more competitive. Check the current I-bond composite rate at TreasuryDirect and compare it to current 10-year TIPS real yield before making large allocations — the relative attractiveness shifts meaningfully with market conditions.
The same state-tax-exemption logic that makes T-bills attractive in high-tax states also applies to I-bonds — both are exempt from state and local tax. For investors in California, New York, or New Jersey, this state-tax advantage widens the I-bond edge in taxable accounts further.
What to Do Right Now
Two actions worth taking this month:
First, open a TreasuryDirect account at treasurydirect.gov if you don’t have one. The setup takes about 20 minutes and you can make your $10,000 I-bond purchase immediately. There’s no reason to delay — I-bonds earn interest from the day of purchase, and the annual limit doesn’t roll over.
Second, check whether your IRA or 401(k) offers a TIPS or inflation-protected bond fund. If it does, and if your current fixed-income allocation is entirely nominal bonds (no inflation protection), consider whether 10-20% of that fixed income bucket should shift to TIPS. This is a rebalancing decision, not an all-or-nothing move.
For deeper reading on inflation-protected investing, David Swensen’s Unconventional Success covers TIPS allocation in institutional-quality terms that translate well to individual portfolio construction. And for a broader treatment of inflation’s long-run impact on retirement portfolios, William Bernstein’s The Four Pillars of Investing remains one of the clearest explanations of how to think about real versus nominal returns over multi-decade time horizons.