I Bonds vs TIPS: Two Ways to Protect Against Inflation
I Bonds vs TIPS Comparison
| Factor | I Bonds | TIPS |
|---|---|---|
| Issuer | US Treasury (TreasuryDirect.gov) | US Treasury (tradeable market) |
| Inflation Adjustment | Composite rate = fixed + CPI variable | Principal adjusts with CPI; coupon is fixed % |
| Purchase Limit | $10,000/person/year (electronic) | No limit |
| Minimum Investment | $25 | $100 (auction) or $1 via ETFs |
| Liquidity | Locked 1 year; 3-month penalty if sold before 5 years | Fully tradeable on secondary market |
| Market Price Risk | None — redeemed at adjusted value | Yes — TIPS prices fluctuate with real rates |
| Tax Treatment | Federal tax; state-exempt; can defer federal until redemption | Federal tax; state-exempt; phantom income tax issue |
| Deflation Protection | Value never drops below purchase price | Guaranteed minimum of original par at maturity |
| Maturities | 30 years (redeemable after 1 year) | 5, 10, and 30 years |
When I Bonds Win
I Bonds are ideal for smaller savers and risk-averse investors. You can’t lose principal (the value never drops below what you paid), there’s no market price volatility, and you can defer federal taxes until redemption. The fixed-rate component plus CPI adjustment has historically delivered solid real returns during inflationary periods.
The $10,000 annual purchase limit is the main constraint. For an emergency fund or short-term savings that need inflation protection, I Bonds are nearly unbeatable after the 1-year lockup expires.
When TIPS Win
TIPS have no purchase limits, making them the choice for large portfolios needing inflation protection. They’re also available through ETFs (like TIP or VTIP), enabling easy diversification across maturities. Institutional investors, retirement funds, and anyone needing significant inflation-hedged exposure uses TIPS.
The trade-off is market risk: TIPS prices fluctuate with real interest rates. When real rates rise, TIPS lose market value — a painful reality in 2022 when TIPS funds declined significantly. Hold to maturity to avoid this risk.
The “Phantom Income” Problem with TIPS
TIPS have a unique tax quirk: as the principal adjusts upward with inflation, you owe federal tax on that adjustment each year — even though you haven’t received the cash. This “phantom income” makes TIPS less tax-efficient in taxable accounts. Hold TIPS in tax-advantaged accounts (Roth IRA, 401(k)) to avoid this issue.
Key Takeaways
- I Bonds offer no market risk, tax-deferral, and guaranteed inflation protection — but limited to $10K/year.
- TIPS have no purchase limits and trade freely, but carry market price risk and phantom income tax issues.
- Both are backed by the US government and adjust for CPI inflation — the core mechanism is similar.
- Hold TIPS in tax-advantaged accounts to avoid the phantom income problem.
- I Bonds first (up to the limit), then TIPS for additional inflation-protected allocation.
Frequently Asked Questions
Can I Bonds lose value?
No. The composite rate can drop to 0% during deflation, but the value never falls below the purchase price. This is a key advantage over TIPS, which can lose market value before maturity.
How is the I Bond rate calculated?
The composite rate combines a fixed rate (set at purchase, lasts 30 years) and a variable rate that resets every 6 months based on CPI-U inflation. The formula is: Composite = Fixed + (2 x Semiannual Inflation) + (Fixed x Semiannual Inflation).
What is phantom income on TIPS?
When TIPS principal increases with inflation, the IRS taxes that increase as income — even though you don’t receive the cash until maturity. This creates a tax liability on unrealized gains, making TIPS inefficient in taxable accounts.
Can I buy TIPS through an ETF?
Yes. Popular TIPS ETFs include iShares TIPS Bond ETF (TIP) for broad exposure and Vanguard Short-Term Inflation-Protected Securities ETF (VTIP) for lower duration risk. ETFs solve the minimum investment and liquidity constraints of individual TIPS.
Which is better during high inflation?
Both perform well during sustained inflation since they adjust with CPI. I Bonds may edge out TIPS because their value can’t drop from market forces. TIPS prices can still fall during inflation if real rates are also rising (as happened in 2022).