Eagle carrying hat filled with I bonds
The March CPI data was released recently.  That means we can now estimate what the new I bond inflation rate will be for the upcoming May 1 change.


I bonds

We now have the data to estimate what the new I bond inflation rate will be for the upcoming May 1 change.

I bonds pay a combination of a fixed rate and an inflation rate.  The current rate through April 30, 2023 is 6.89%.  This is made up of 0.4% fixed rate + 6.48% inflation rate.

Every May 1 and November 1 the U.S. Treasury announces the I bond fixed rate and inflation rate.  The U.S. Treasury does not tell us how the fixed rate is determined.  However, we can estimate the I bond inflation rate.

How the I bond Inflation Rate is determined

The inflation rate can, and usually does, change every 6 months.  According to treasurydirect.gov, the inflation rate on changes in the non-seasonally adjusted Consumer Price Index for all Urban Consumers (CPI-U)> for all items, including food and energy.

We now have the CPI date from September 2022 to March 2023 to estimate the I bond inflation rate.  The predicted new rate is 3.39%.  Here is a table with the CPI data and six-month change. 

MonthObservation Value6-month change x 2
2022 Sep296.808  
2022 Oct298.012  
2022 Nov297.711  
2022 Dec296.797  
2023 Jan299.170  
2023 Feb300.840  
2023 Mar301.8361.69%3.39%

The six month change in CPI was 1.69% which you need to multiply by 2 to get the annual rate of 3.39%.

Source of data: https://data.bls.gov/cgi-bin/surveymost

Buy Now or Buy Later

The question for all of us is should I buy I Bonds now or wait until after May 1?

With the inflation rate changing from 6.45% to 3.39%, that is about a 3% drop.  It seems pretty compelling to buy I bonds before April 28.

If you think the fixed rate is going up much higher than the current 0.4%, you could wait.  Remember that fixed rate could also drop to zero.

I bond historical rates

Maybe looking at historical data will help you with this decision.  Let’s look at the past several years of I bond interest rate data.  Here is a chart going back to May 2015, the last time there was a negative 6-month inflation rate.

 Fixed Rate6 month Inflation RateAnnualized Inflation RateTotal I bond rate




As the saying goes, a bird in the hand is better than two in the bush.  The Moven Maven thinks rather than risking the 3..09% difference in interest for 6 months by betting on a higher fixed rate – buy now.  You should not wait until April 28 to buy.  The treasury direct website has gotten overwhelmed at times.  If you want the current rate of 6.89%, buy your I bonds soon.


Leave a Reply

Your email address will not be published. Required fields are marked *

A note to our visitors

This website has updated its privacy policy in compliance with changes to European Union data protection law, for all members globally. We’ve also updated our Privacy Policy to give you more information about your rights and responsibilities with respect to your privacy and personal information. Please read this to review the updates about which cookies we use and what information we collect on our site. By continuing to use this site, you are agreeing to our updated privacy policy.