Series I Savings Bonds — commonly called “I Bonds” — are US Treasury securities designed to protect your savings from inflation. The interest rate on I Bonds has two components: a fixed rate (locked in at purchase for the life of the bond) and a variable rate that adjusts every six months based on the Consumer Price Index (CPI-U). When inflation is high, I Bonds pay unusually high rates; when inflation falls, the rate falls too.
Key takeaway: I Bonds are government-guaranteed, state-tax-exempt, and inflation-linked — making them a useful tool for short-to-medium-term savings (1–5 years) when inflation protection matters. The annual purchase limit of $10,000 per person per year limits their role as a major portfolio holding, but they’re worth understanding for cash savings goals like emergency funds or college savings.
I Bond Rate Explained — 2026
| Component | Detail |
|---|---|
| Fixed rate | Set at purchase; stays the same for the life of the bond |
| Variable inflation rate | Adjusted every May 1 and November 1 based on prior 6 months of CPI-U |
| Composite rate formula | Fixed rate + (2 × Semiannual inflation rate) + (Fixed rate × Semiannual inflation rate) |
| Rate check | Visit TreasuryDirect.gov for current composite rate |
| Rate period | Current rate applies for 6 months from purchase date |
The rate you earn rotates every 6 months after your purchase date — not on May 1 / November 1 specifically. So if you buy in March, your first rate applies March–August; your second rate (based on the May announcement) applies September–February.
I Bond Purchase Limits — 2026
| Purchase method | Annual limit per SSN |
|---|---|
| Electronic (TreasuryDirect.gov) | $10,000 |
| Paper bonds (via tax refund, Form 8888) | $5,000 |
| Total per person | $15,000/year |
| Married couple (combined) | Up to $30,000/year |
| Trust | $10,000 per trust per year |
I Bond Holding Periods and Penalties
| Holding period | Rules |
|---|---|
| Under 12 months | Cannot redeem — completely illiquid |
| 12 months – 5 years | Redeemable, but forfeit last 3 months of interest |
| After 5 years | Redeem any time with no penalty |
| After 30 years | Bond stops earning interest; must redeem |
Practical implication: If you buy an I Bond today and redeem in exactly 12 months, you receive 9 months of interest (the last 3 months are forfeited). After 15 months, you receive 12 months. After 5 years, you receive all interest accumulated.
How I Bond Interest Is Calculated
Example — $10,000 I Bond at 4.28% composite rate (hypothetical 2026 rate)
| Period | Rate Applied | Interest Earned |
|---|---|---|
| Months 1–6 | 4.28% composite | $214 |
| Months 7–12 | Updated rate (depends on next announcement) | Varies |
| At 12 months (before penalty) | ~$428 gross | Minus 3-month penalty |
| Net at 12-month redemption | ~$321 |
Interest compounds semiannually — it’s added to your principal every 6 months, and future interest is earned on the higher balance.
I Bond Tax Treatment
Federal tax: Yes — I Bond interest is federally taxable. You choose:
- Accrue annually — report interest each year on Form 1040 (Schedule B) even before cashing
- Defer until redemption — most people choose this; report all interest in the year you cash the bond
State/local tax: Completely exempt — a significant advantage over CDs and high-yield savings accounts if you live in a high-income-tax state.
Education exclusion: If you redeem I Bonds to pay qualified higher education expenses (tuition/fees) for yourself, spouse, or dependent at an eligible institution, the interest may be partially or fully excluded from federal tax. Income limits apply — phase-out begins around $145,000 (MFJ) in 2026. See IRS Form 8815.
I Bonds vs Treasury Bills vs High-Yield Savings Accounts
| Feature | I Bonds | T-Bills | High-Yield Savings Account |
|---|---|---|---|
| Rate type | Inflation-linked (variable) | Fixed for term | Variable |
| State/local tax | Exempt | Exempt | Taxable |
| Annual limit | $10,000 per person | Unlimited | Unlimited |
| Minimum hold | 12 months | 4 weeks | None |
| Early withdrawal penalty | Yes (3 months interest if under 5 years) | None (secondary market) | None for most |
| FDIC/gov backing | US Treasury | US Treasury | FDIC (bank) |
| Best for | Inflation hedge, 1–5 year horizon | Flexible short-term cash | Emergency fund, flexibility |
Who Should Buy I Bonds?
Good fit:
- Savers who want inflation protection for money they won’t need for 12+ months
- High-income residents of high-tax states (state tax exemption adds real value)
- Parents saving for college (education exclusion possible)
- Investors who’ve maxed out other tax-advantaged options
Not ideal for:
- Emergency fund (12-month lockup is problematic for emergencies)
- Short-term savings goals (under 12 months)
- Building a large bond portfolio (purchase limits constrain portfolio size)
How to Buy I Bonds
- Create an account at TreasuryDirect.gov
- Link your US bank account
- Purchase in any amount from $25 to $10,000 (electronic); fractional amounts allowed
- Bond is issued within 1 business day
- Manage, track, and redeem via TreasuryDirect.gov
Related Resources
- Treasury Bills Guide — short-term government securities
- Bond Investing 2026 — complete bond investing guide
- Asset Location Strategy — where to hold bonds for tax efficiency
- High-Yield Savings vs CDs — cash savings alternatives
The content on Wealthvieu is for informational purposes only and should not be considered financial, tax, or investment advice. Consult a qualified professional before making financial decisions. Full disclaimer · Editorial policy