In 2022, Series I savings bonds became the most talked-about personal finance product since the Roth IRA. The composite rate hit 9.62% annualized for six months — triple what any FDIC-insured savings account was offering. People who had never heard of TreasuryDirect.gov were suddenly opening accounts and maxing out the $10,000 annual purchase limit.
That era is over. In 2025, the I-Bond composite rate has settled into the 3.1%-3.5% range, depending on the current six-month rate cycle. Meanwhile, high-yield savings accounts at online banks — Marcus, Ally, Discover, SoFi, LendingClub — are offering 4.2%-4.8% APY with no lock-up, no penalty for withdrawal, and full liquidity from day one.
On the surface, the HYSA wins. But surface math is not the right math. I-Bonds have a structural tax advantage that HYSA interest does not, and depending on where you live and how long you hold, that advantage can flip the outcome. Here is the complete comparison.
How I-Bond Rates Work (And Why the "Current Rate" Is Never the Whole Story)
The Fixed Rate + Variable Rate Structure Most Explainers Skip Over
Every I-Bond has two rate components:
The fixed rate: Set at the time of purchase. Stays locked for the 30-year life of the bond. This rate has historically been 0%-0.5% — for most of 2019-2022, it was 0.00%. In 2023-2024, it climbed back into positive territory (0.9%-1.3%), which matters a lot for the long-term value of bonds purchased in that window.
The variable (inflation) rate: Resets every May 1 and November 1 based on the Consumer Price Index change from the prior six-month period. This is the component that drove the 9.62% composite rate in 2022 and has since returned to more modest levels as inflation has cooled.
The composite rate formula: fixed rate + (2 × semiannual CPI rate) + (fixed rate × semiannual CPI rate). In plain terms: your bond earns the fixed rate plus twice the six-month inflation reading, annualized.
As of mid-2025, the composite rate is approximately 3.1%-3.5% depending on the current cycle. I-Bond rates reset for each six-month period, so a bond purchased today will earn the current composite rate for its first six months, then the new rate (announced May or November) for the next six months, and so on for the 30-year life of the bond. Check TreasuryDirect.gov for the precise current rate before purchasing — it changes twice a year and the current article uses approximate 2025 figures.
The Liquidity Reality: The Cost of That 3-Month Penalty
The Number That Changes the Effective Yield in Year One
I-Bonds cannot be redeemed at all for the first 12 months after purchase. This is a hard stop — there is no exception for emergencies, no secondary market to sell on. If you buy an I-Bond today and need the money in 11 months, you cannot access it.
Between months 12 and 60 (1-5 years after purchase), you can redeem — but you forfeit the last 3 months of interest. At a 3.5% composite rate, that penalty equals approximately 0.875% of principal. On $10,000: an $87.50 penalty.
The effective yield calculation at different hold periods:
Redeemed at exactly 12 months (minimum hold): You earned 12 months of interest, but the penalty removes 3 months. Effective yield: approximately 3.5% × (9/12) = 2.625%. This is significantly below what a HYSA at 4.5% would return over the same 12 months (4.5%).
Redeemed at 24 months: 24 months of interest minus 3 months penalty. Effective yield: 3.5% × (21/24) = 3.06%. Still below the HYSA, before taxes.
Redeemed at 5 years or beyond: No penalty. Full 3.5% average annualized. The tax advantage now becomes meaningful.
The practical implication: I-Bonds held for only 12-18 months are rarely the better choice versus a HYSA at current rates, even before factoring in taxes. The holding period at which they become competitive — especially in high-tax states — is closer to 3-5 years.
The After-Tax Comparison: Where I-Bonds Win
The State Tax Exemption Most People Underestimate
I-Bond interest is subject to federal income tax (at ordinary income rates, in the year of redemption). It is exempt from state and local income taxes entirely. This is a meaningful structural advantage in high-tax states.
HYSA interest is taxable at federal, state, and local rates — every dollar of interest earned is taxable income in the year it is paid.
The after-tax comparison on $10,000 over 3 years (holding to avoid the penalty period):
Scenario A: California resident, 22% federal bracket, 9.3% state income tax
HYSA at 4.5% APY: $10,000 grows to approximately $11,411 before tax over 3 years. Interest earned: $1,411. Federal + state tax rate: 31.3%. Tax: $441. After-tax total: ~$10,970
I-Bond at 3.5% composite (no penalty at 3 years): $10,000 grows to approximately $11,087. Interest earned: $1,087. Federal tax only at 22%: $239. After-tax total: ~$10,848
At these rates, HYSA still wins in California by about $122 over 3 years. But notice how close it is. If the HYSA rate drops to 3.8% (possible as the Fed continues rate adjustments) while the I-Bond stays at 3.5%, the gap flips — I-Bond wins after the California state tax exemption.
Scenario B: Texas resident, 22% federal, 0% state
HYSA at 4.5%: After 22% federal tax on $1,411 = $311 tax. After-tax total: ~$11,100
I-Bond at 3.5%: After 22% federal on $1,087 = $239. After-tax total: ~$10,848
HYSA wins clearly in Texas — the state tax exemption advantage disappears when state tax is zero.
The math is clear: I-Bonds are most competitive for residents of high-tax states (California, New York, New Jersey, Minnesota, Oregon) who plan to hold for 3+ years. The further into zero-tax-state territory you are, the harder I-Bonds work to compete on after-tax return.
The Four Scenarios Where I-Bonds Still Win in 2025
1. You live in a high income-tax state and plan to hold for 5+ years. California (9.3%), New York (6.85%-10.9%), New Jersey (6.37%), Minnesota (9.85%), Oregon (9.9%). At 5+ years, the penalty is gone, and the state tax exemption on every dollar of interest compounding is real money over a long hold. This is not emergency fund territory — this is money you genuinely won't need for several years.
2. You expect inflation to accelerate over your holding period. This is the core I-Bond design proposition: the variable rate automatically adjusts upward with CPI. If inflation runs hot in 2026-2027 (not impossible — supply chain shocks, energy events, deficit spending), your I-Bond rate resets upward while a fixed HYSA rate lags. HYSA rates do eventually follow the Federal Funds Rate, but with delay and sometimes significant lag. The I-Bond inflation adjustment is mechanical and guaranteed.
3. You have children approaching college and qualify for the education exclusion. I-Bond interest is entirely exempt from federal income tax when redeemed for qualified higher education expenses — tuition, fees, and sometimes room and board — if your income is below the threshold ($96,800 filing single, $145,200 married filing jointly for 2025, phasing out above those levels). At moderate income levels with kids in high school, this turns the I-Bond into an education savings vehicle with tax-free returns. The 529 plan is usually better for dedicated college savings, but if you're already maxing a 529 and have additional savings, this exclusion is worth knowing.
4. You want set-it-and-forget-it inflation protection for a specific future expense. If you know you need $10,000 in exactly 5 years for a planned home renovation, a vehicle, or a specific goal, the I-Bond holds that purchasing power automatically. You don't need to worry about whether HYSA rates decline — the I-Bond adjusts. For money with a clear purpose date 5+ years out, the structural inflation protection has value beyond the rate comparison.
The Four Scenarios Where HYSA Is Clearly Better
1. You need the money within 12 months. There is no debate here. I-Bonds cannot be redeemed for the first 12 months. If there is any realistic possibility you'll need these funds — for an emergency fund, a down payment timeline, a planned purchase — HYSA is the only choice. The $10,000 annual I-Bond limit is also non-recoverable: you can't buy an extra $10,000 next year to make up for a year you skipped.
2. You live in a no-income-tax state. Florida, Texas, Washington, Nevada, Wyoming, South Dakota, Tennessee (investment income), New Hampshire (investment income). Without a state tax to exempt, I-Bonds lose their primary structural advantage. HYSA wins on rate and liquidity.
3. You've already hit the $10,000 annual limit. The per-person annual purchase limit is $10,000 from TreasuryDirect.gov plus $5,000 via federal tax refund (paper bonds only). For couples, the limit is $20,000/year combined. Once you've maxed it, the comparison is moot — excess savings go to HYSA regardless.
4. The rate differential exceeds 2 percentage points. If a HYSA is offering 4.8% and I-Bonds are at 3.1%, the 1.7-point gap is too wide for the state tax exemption to close for most people. The math has to be run at your specific state tax rate, but as a rough rule: if the gap is under 1.5 points, high-tax-state residents should run the comparison. Above 2 points, HYSA wins in most scenarios even with the state exemption.
How to Buy I-Bonds and What to Do First
I-Bonds are purchased exclusively through TreasuryDirect.gov — not through your brokerage, not through your bank. You need to create a TreasuryDirect account with your Social Security number, bank account information, and basic personal details. The process takes about 15 minutes. Purchases take one business day to settle.
The $10,000 annual limit resets January 1. If you're planning to buy, the best strategy is to buy as early in the calendar year as possible — January purchases earn interest for the full year. Bonds purchased in December only earn interest for a partial year, and the purchase limit resets in January anyway.
For savings strategy beyond I-Bonds — understanding how HYSA, I-Bonds, and taxable investment accounts fit together across different time horizons — our guide to prioritizing savings when you have $5,000 walks through the full savings waterfall and when each account type belongs. For the related question of how tax-advantaged accounts compare when you're deciding where to put additional savings beyond your emergency fund, our comparison of taxable brokerage vs additional 401k contributions after maxing a Roth IRA covers that three-way decision with the same after-tax framework. And our analysis of whether to max an HSA or Roth IRA first is the same tax-optimization lens applied to two other vehicles — the underlying question is always "what does this money actually cost in taxes, and what's the right account for the goal?"
Two books worth having on the shelf if you're actively optimizing your savings across HYSA, I-Bonds, and investment accounts: I Will Teach You to Be Rich by Ramit Sethi is the most practical guide to setting up an automated savings system — he covers exactly how to use HYSAs as the foundation, and the framework for deciding what money goes where. And The Psychology of Money by Morgan Housel is the clearest treatment of why the "optimal" financial decision often isn't the one you can actually stick with for 30 years — a perspective that directly applies to the I-Bonds vs HYSA choice, where the tax math may favor I-Bonds but the behavioral cost of locking money up for 12 months needs to be priced in honestly.