I Bonds and Treasury bonds are both issued by the US government, but they work very differently. I Bonds protect against inflation with adjusting rates and purchase limits. Treasury bonds pay fixed income with no purchase cap but expose you to interest rate risk. Here’s how to choose between them.
I Bonds vs Treasury Bonds: Quick Comparison
| Feature | I Bonds (Series I Savings Bonds) | Treasury Bonds (T-Bonds) |
|---|---|---|
| Current rate | 3.68% (composite) | 4.50-4.75% (fixed coupon) |
| Rate type | Fixed + inflation-adjusted (changes every 6 months) | Fixed coupon for life of bond |
| Inflation protection | ✅ Built in | ❌ None |
| Terms | 30 years (redeemable after 12 months) | 20 or 30 years |
| Purchase limit | $10,000/person/year (electronic) + $5,000 paper | No limit |
| Minimum purchase | $25 | $100 |
| Where to buy | TreasuryDirect.gov only | Auction, brokerage, or secondary market |
| Tradeable | ❌ (redeem with Treasury only) | ✅ (trades on secondary market) |
| Price fluctuation | None (always redeemed at accrued value) | Yes (market price changes with rates) |
| Interest payments | Accrues (paid at redemption) | Semiannual coupon payments |
| State/local tax | Exempt | Exempt |
| Federal tax | Taxable (can defer until redemption) | Taxable (each coupon payment) |
| Early redemption | After 12 months (3-month penalty if before 5 years) | Sell on secondary market anytime |
| Can lose value | No | Yes (if sold before maturity when rates rise) |
How Each Bond Works
I Bonds
I Bonds pay a composite rate made up of two parts:
| Component | Current (2026) | How It Works |
|---|---|---|
| Fixed rate | 1.20% | Set at purchase, never changes for the life of the bond |
| Inflation rate | 2.48% | Adjusts every 6 months based on CPI |
| Composite rate | 3.68% | Your actual earnings rate |
The inflation component can go up or down (but the composite rate can never go below 0%). When inflation is high, I Bonds pay more. When inflation is low, they pay less — but your fixed rate provides a floor.
Treasury Bonds
Treasury bonds pay a fixed coupon rate for 20 or 30 years:
| Feature | Details |
|---|---|
| Coupon rate | Fixed at auction (currently 4.50-4.75%) |
| Interest payments | Every 6 months |
| Face value | $100 per bond |
| At maturity | Receive full face value ($100 per bond) |
| Market price | Fluctuates daily based on interest rates |
The key difference: your coupon rate never changes, but the bond’s market price moves inversely with interest rates. If rates rise after you buy, your bond’s market price falls. If rates fall, your bond’s price rises.
Rate and Earnings Comparison
Current Rates (March 2026)
| Bond | Nominal Rate | Inflation Adjustment | Effective Yield |
|---|---|---|---|
| I Bond | 3.68% | Automatic (every 6 months) | Tracks inflation + 1.20% |
| 20-Year Treasury Bond | 4.65% | None | 4.65% fixed |
| 30-Year Treasury Bond | 4.50% | None | 4.50% fixed |
Earnings on $10,000 Over Time
Assumes 2.5% average inflation going forward:
| Period | I Bond (~3.70% avg*) | 30-Year T-Bond (4.50% fixed) |
|---|---|---|
| Year 1 | $368 | $450 |
| Year 5 | $1,990 | $2,250 |
| Year 10 | $4,372 | $4,500 |
| Year 20 | $10,370 | $9,000 |
| Year 30 | $18,610 | $13,500 |
*I Bond rate varies with inflation — this assumes 2.5% inflation + 1.20% fixed rate.
Key insight: Treasury bonds pay more in the early years when their fixed rate is higher. I Bonds can pay more over the long term if inflation remains at or above the level baked into Treasury bond yields.
If Inflation Rises to 4%
| Period | I Bond (~5.20% avg) | 30-Year T-Bond (4.50% fixed) |
|---|---|---|
| Year 5 | $2,878 | $2,250 |
| Year 10 | $6,590 | $4,500 |
| Year 20 | $17,540 | $9,000 |
If Inflation Falls to 1%
| Period | I Bond (~2.20% avg) | 30-Year T-Bond (4.50% fixed) |
|---|---|---|
| Year 5 | $1,147 | $2,250 |
| Year 10 | $2,431 | $4,500 |
| Year 20 | $5,413 | $9,000 |
I Bonds win in high-inflation environments. Treasury bonds win in low-inflation environments.
Purchase Limits and Access
| Factor | I Bonds | Treasury Bonds |
|---|---|---|
| Annual purchase limit | $10,000 electronic + $5,000 paper | No limit |
| Minimum investment | $25 | $100 |
| Maximum per year (individual) | $15,000 | Unlimited |
| Maximum per year (couple) | $30,000 | Unlimited |
| Maximum per year (with trusts/LLCs) | $50,000+ | Unlimited |
| Where to buy | TreasuryDirect.gov (paper via tax refund) | TreasuryDirect, Fidelity, Schwab, any brokerage |
| Gift options | Yes (TreasuryDirect) | Yes (transfer through brokerage) |
Maximizing I Bond Purchases
| Method | Annual Amount |
|---|---|
| You (electronic) | $10,000 |
| You (paper via tax refund) | $5,000 |
| Spouse (electronic) | $10,000 |
| Spouse (paper via tax refund) | $5,000 |
| Trust (electronic) | $10,000 |
| LLC/business (electronic) | $10,000 |
| Maximum (couple + entities) | $50,000+ |
The $10,000 limit is I Bonds’ biggest limitation. Treasury bonds have no purchase cap, making them practical for large allocations.
Liquidity and Price Risk
| Factor | I Bonds | Treasury Bonds |
|---|---|---|
| Minimum holding period | 12 months | None (sell anytime) |
| Early redemption penalty | Lose 3 months interest (if within 5 years) | No penalty (but price may differ) |
| Price risk | None (always redeem at full accrued value) | Yes (price fluctuates with rates) |
| Secondary market | ❌ Not tradeable | ✅ Highly liquid |
| Sell for a gain | Not possible (no market price) | ✅ If rates fall |
| Sell for a loss | Not possible | ✅ If rates rise |
Treasury Bond Price Sensitivity (Duration Risk)
A 30-year Treasury bond has high interest rate sensitivity:
| Rate Change | Approximate Price Change (30-Year) |
|---|---|
| Rates rise 0.50% | Price drops ~8% |
| Rates rise 1.00% | Price drops ~15% |
| Rates rise 2.00% | Price drops ~27% |
| Rates fall 0.50% | Price rises ~9% |
| Rates fall 1.00% | Price rises ~18% |
| Rates fall 2.00% | Price rises ~40% |
If you buy a $10,000 30-year Treasury bond and rates rise 1%, your bond is worth approximately $8,500 on the secondary market. You still get $10,000 if you hold to maturity, but you’re locked into a below-market rate for potentially decades.
I Bonds never have this problem — your principal is always whole and your rate adjusts with inflation.
Inflation Protection Comparison
| Scenario | I Bonds | Treasury Bonds |
|---|---|---|
| Inflation rises | Rate increases automatically | Fixed rate — purchasing power erodes |
| Inflation stays moderate | Rate reflects current CPI | Fixed rate may exceed inflation |
| Inflation drops | Rate decreases (but never below 0%) | Fixed rate looks increasingly attractive |
| Deflation | Composite rate floors at 0% (value never drops) | Fixed rate remains — you gain purchasing power |
Real Return (After Inflation)
| Inflation Rate | I Bond Real Return | T-Bond Real Return (4.50% coupon) |
|---|---|---|
| 1.0% | ~1.20% (the fixed rate) | ~3.50% |
| 2.5% | ~1.20% | ~2.00% |
| 4.0% | ~1.20% | ~0.50% |
| 5.0% | ~1.20% | -0.50% (losing purchasing power) |
| 7.0% | ~1.20% | -2.50% |
I Bonds deliver a consistent real return equal to your fixed rate, regardless of inflation. Treasury bonds’ real return depends entirely on where inflation ends up.
Tax Treatment
Both I Bonds and Treasury bonds are exempt from state and local income taxes. But they differ on when you pay federal taxes.
| Tax Feature | I Bonds | Treasury Bonds |
|---|---|---|
| Federal income tax | Taxable | Taxable |
| State/local income tax | Exempt | Exempt |
| When taxed (default) | At redemption (tax deferral) | Each coupon payment |
| Option to pay annually | Yes (can elect to report annually) | N/A (taxed as received) |
| Education tax exclusion | ✅ (if qualified) | ❌ |
| Estate tax | Included in estate | Included in estate |
I Bond Education Tax Exclusion
I Bond interest can be completely tax-free if used for qualified higher education expenses:
- Must be age 24+ when the bonds were purchased
- Must use for tuition/fees at eligible institutions (for you, spouse, or dependents)
- Income limits apply: phased out at $100,800-$130,800 for single filers, $158,650-$188,650 for joint filers (2026)
Treasury bonds have no equivalent education benefit.
Tax Deferral Advantage
With I Bonds, you can defer all federal taxes until you actually redeem the bond — potentially decades. This creates a compounding advantage:
| Strategy | $10,000 Over 10 Years (3.68% rate, 24% bracket) |
|---|---|
| I Bond (tax deferred) | $10,000 → $14,372 → pay tax at redemption |
| T-Bond (taxed annually) | Less compounding due to annual tax drag |
The deferral means more of your money compounds over time.
I Bonds vs Treasury Bonds vs TIPS
Treasury Inflation-Protected Securities (TIPS) are another inflation-protected government bond:
| Feature | I Bonds | Treasury Bonds | TIPS |
|---|---|---|---|
| Inflation protection | ✅ | ❌ | ✅ |
| Purchase limit | $10K/year | None | None |
| Tradeable | ❌ | ✅ | ✅ |
| Price risk | None | High (long-term) | Moderate |
| Current real yield | 1.20% | N/A | 1.80-2.10% |
| Minimum | $25 | $100 | $100 |
| Terms | 30 years (redeem after 1) | 20-30 years | 5, 10, 30 years |
| Interest payments | Accrues | Semiannual | Semiannual (on adjusted principal) |
| State/local tax | Exempt | Exempt | Exempt |
| Can lose market value | No | Yes | Yes |
TIPS are the middle ground: inflation protection like I Bonds with no purchase limit like Treasury bonds, but with price risk if sold before maturity. Currently, TIPS offer a slightly higher real yield (1.80-2.10%) than I Bonds’ 1.20% fixed rate.
Who Should Choose I Bonds?
✅ You want guaranteed inflation protection with zero risk of loss
✅ You can invest up to $10,000-$15,000/year (within the limit)
✅ You want tax deferral — don’t pay taxes until you redeem
✅ You may use proceeds for education expenses (tax-free interest)
✅ You want a safe savings vehicle you can hold for 1-30 years
✅ You’re worried about future inflation and want automatic protection
✅ You want simplicity — no market prices to watch, no trading
Who Should Choose Treasury Bonds?
✅ You want to invest more than $10,000/year in government bonds
✅ You want regular income — semiannual coupon payments
✅ You’re building a bond ladder or fixed-income portfolio
✅ You believe inflation will stay low — fixed rate beats adjustable
✅ You want the option to sell for a gain if rates fall
✅ You need portfolio diversification — bonds offset stock volatility
✅ You’re investing through a brokerage (401k, IRA, taxable account)
Best Strategy: Use Both
I Bonds and Treasury bonds serve complementary roles in a diversified portfolio:
| Allocation | Vehicle | Purpose |
|---|---|---|
| Inflation hedge ($10K-$50K) | I Bonds (max annually) | Guaranteed real return, zero price risk |
| Fixed income allocation | Treasury bonds or bond ETFs | Regular income, portfolio ballast |
| Emergency reserves | I Bonds (after 12-month holding period) | Safe, inflation-protected near-cash |
| Large bond allocation | Treasury bonds/TIPS | No purchase limit, brokerage-accessible |
| Education savings | I Bonds | Potential tax-free interest |
Portfolio Example: $200,000 Bond Allocation
| Vehicle | Amount | Purpose | Yield |
|---|---|---|---|
| I Bonds (built over 5 years) | $50,000 | Inflation protection, tax deferral | 3.68% (adjusts) |
| 10-Year TIPS | $50,000 | Inflation protection, larger allocation | 2.10% real + CPI |
| 20-Year Treasury Bonds | $50,000 | Fixed income, portfolio diversification | 4.65% fixed |
| Short-Term Treasury ETF (SHY) | $50,000 | Liquidity, low duration risk | 4.50% |
Bottom Line
| Category | Winner |
|---|---|
| Inflation protection | I Bonds (automatic, guaranteed) |
| Current nominal rate | Treasury bonds (4.50% vs 3.68%) |
| Real return (after inflation) | TIPS > I Bonds > Treasury bonds (depends on inflation) |
| Price safety | I Bonds (never lose value) |
| Purchase flexibility | Treasury bonds (no limit) |
| Liquidity | Treasury bonds (sell anytime on market) |
| Tax deferral | I Bonds (defer until redemption) |
| Education tax benefits | I Bonds (potentially tax-free) |
| Income generation | Treasury bonds (semiannual coupons) |
| Portfolio integration | Treasury bonds (brokerage, ETFs, 401k) |
| Simplicity | I Bonds (no market, no trading) |
| Best for most savers | I Bonds (up to the limit) |
I Bonds are the better choice for most individual savers — they protect against inflation, can’t lose value, offer tax deferral, and may be tax-free for education. The only real drawback is the $10,000/year purchase limit. Treasury bonds are better for larger allocations where you need more than $10,000/year, want regular income, or are building a diversified bond portfolio within a brokerage or retirement account. The smartest strategy: buy I Bonds up to the annual limit for inflation protection, then use Treasury bonds (or TIPS) for the rest of your fixed-income allocation.
Related: I Bonds Guide | CDs vs Treasury Bills | HYSA vs Treasury Bills | High-Yield Savings vs CD | Best Savings Accounts