I-Bond May 2027 Fixed-Rate Decision Calculator
Treasury resets Series I Bond fixed rate every May 1 and Nov 1. Current fixed rate 1.20%. Should you buy now or wait for the May 2027 reset? Calculate based on your inflation forecast. Source: treasurydirect.gov.
How I-Bond Composite Rate Works
Composite Rate = Fixed Rate + (2 × Variable Rate) + (Fixed × Variable). Fixed Rate set when bought, locked for 30 years. Variable Rate set every May 1 and Nov 1 based on prior 6-month CPI-U change. Current composite ~3.11% reflects 1.20% fixed + ~1.90% annualized inflation. Source: treasurydirect.gov.
Why Fixed Rate Matters More Than You Think
Fixed rate compounds over the bond's 30-year life. A 0.30% higher fixed rate on $10,000 over 30 years = ~$1,000+ in extra purchasing power. Locking in higher fixed rate beats waiting for marginally higher variable (which adjusts every 6 months anyway). Historical fixed rates: 0.00% (2008-2018), 0.50-1.30% recent peaks.
Timing the Reset Window
Strategy: if you expect the next May/Nov reset to LOWER fixed rate, buy NOW to lock current. If you expect HIGHER fixed rate, wait. Treasury sets fixed based on long-term real yields (5/10-year TIPS). If TIPS real yields rise, expect fixed to rise. If TIPS yields stable/falling, expect fixed to stay or fall.
Annual Purchase Limit and Cycle Strategy
$10,000/SSN/year electronic limit + $5,000 via tax refund (paper). Strategy: max December purchase to lock current year's fixed + capture early-year interest, then buy again in January (new year limit). Effectively $20,000 within 5 weeks. Source: treasurydirect.gov.