Summary
- I Bonds purchased from May to October 2017 will earn a composite rate of 1.96% for six months.
- If you haven’t bought I Bonds in 2017, I suggest waiting until October.
- Terms for EE Bonds didn’t change – their value still doubles after 20 years, making them a very competitive investment for the right buyer.
Treasury Inflation-Protected Securities 
For a person who buys the 10K limit I-Bonds every CY, for sure, a way to think about the three timing choices for the fixed rate:
EARLY January thru April
MIDDLE May thru October
LATE November thru December
It might even come down to:
Early: January or April
Middle: May or October
Late: November
In each of those months you get information that helps guide a decision. And in November, if you haven’t bought before then, you pull the trigger because you want the 10,000 limit.