HYSAs offer total liquidity with variable rates. I-Bonds, issued by the U.S. Treasury, offer rates tied to inflation but enforce strict time locks and penalties on withdrawals.
Savings
I-Bond vs High Yield Savings Calculator: Where to Stash Cash
A breakdown of liquidity rules, state taxes, and interest rates to calculate exactly where your emergency fund belongs.
Published: April 17, 2026
The Fight for Safe Yield
When deciding where to keep your cash reserves, Series I Savings Bonds (I-Bonds) and High Yield Savings Accounts (HYSAs) are the top contenders. However, they structure risk and taxation very differently.
I-Bond Rules and The 3-Month Penalty
When calculating returns on I-bonds, you must understand the restrictions:
- Year 1 Lockup: You cannot cash the bond under any circumstances for the first 12 months. This makes them unsuitable for immediate emergency funds.
- Year 2-5 Penalty: If you cash out before 5 years, you lose the last 3 months of interest.
- Annual Limits: You can only buy $10,000 per person per year electronically.
Calculating the Tax Difference
Don't look at face-value interest rates. Always calculate the "After-Tax Yield."
HYSA interest is taxed at both the federal and state levels. If you live in a high-tax state (like California or New York), state taxes can eat heavily into your returns.
I-Bond interest, on the other hand, is exempt from state and local taxes. For residents of high-tax states, an I-Bond yielding 4% might result in more take-home cash than a HYSA yielding 4.5%.
Frequently Asked Questions
No. You cannot cash them in for the first 12 months. If you cash them in before 5 years, you lose the preceding 3 months of interest.
It depends on inflation. I-Bonds match inflation rates and are exempt from state tax. HYSAs are fully liquid but rates can drop suddenly, and they are taxed at federal and state levels.