I Bond Fixed + Variable Rate
Series I Bonds combine a fixed rate (set at purchase, lasts life of bond) plus a variable inflation rate (resets every 6 months). $10K/yr per person Treasury Direct cap.
| I Bond (Total) gross yield | — |
| I Bond (Total) after tax | — |
| TIPS gross yield | — |
| TIPS after tax | — |
| Winner | — |
I Bond Fixed + Variable Rate compares fixed-income alternatives by after-tax yield. Federal taxability, state-tax exemptions, and inflation indexing all change the winner depending on your tax bracket.
Taxability Matters
Federal income tax, state income tax, and AMT all affect net yield. Treasury obligations are state-tax-exempt. Municipal bonds may be fully tax-free or partially. Corporate bonds fully taxable.
Yield vs Total Return
Yield-to-maturity assumes hold to maturity. Total return includes price changes from rate movements. Long-duration bonds swing more on rate changes.
After-Tax Decision Rule
Compare after-tax yield, not gross yield. High earners in high-tax states often find munis or Treasuries beat corporates net of tax.
FDIC vs Treasury Safety
FDIC insures bank deposits to $250K per depositor per bank. Treasury obligations have full faith and credit, no cap. CDs over $250K need spreading.
Last updated May 2026. Sources: Treasury Direct I Bonds.