Annual U.S. inflation fell to 5.0% in March, but core inflation rose to 5.6%.
By David Enna, Tipswatch.com
Update, April 28, 2023: Treasury raises I Bond’s fixed rate to 0.9%; new composite rate is 4.30%
The just-released U.S. inflation report for March sets the new inflation-adjusted rate for U.S. Series I Savings Bonds at 3.38%, down substantially from the current 6.48%.
The inflation-adjusted rate, often called the I Bond’s variable rate, is based on non-seasonally adjusted inflation from October 2022 to March 2023, which ran at 1.69%. That number is doubled to create the annualized variable rate of 3.38%. Here are the numbers:

This new variable rate will be combined with a fixed rate (also to be reset May 1) to create the I Bond’s new composite rate for purchases from May through October 2023. The variable rate eventually will be applied to all I Bonds for six months, but the launch date depends on the month of the original purchase.
What does this mean for I Bond investors?
My immediate thinking is that this lower variable rate skews the equation toward making an I Bond purchase in April, to capture the current composite rate of 6.89% for a full six months, before transitioning to a 3.79% composite rate for the next six months.
The one unknown is: Will the Treasury raise the I Bond’s fixed rate on May 1? It’s definitely possible. I have been speculating that the fixed rate will end up in a range of 0.4% to 0.6% at the reset. No one knows. I will be writing more about this later this week.
Another consideration: Investors looking for short-term yield may want to skip buying I Bonds at this point. I Bonds purchased before May 1 will offer an annual compounded return of about 5.4%, which is very attractive. But redeeming before 5 years incurs a three-month interest penalty. That drops the annual return to about 4.4%, slightly less than a 1-year Treasury bill at 4.7%.
Does this fall in the variable rate mean I Bonds are no longer an attractive investment? Absolutely not, but it does probably mark the end of the explosively high demand for I Bonds, caused by successive variable rates of 7.12%, 9.62% and 6.48%. Back to reality: I Bonds should be viewed as an ultra-safe investment that will track or exceed U.S. inflation for as long as you hold them.
As I noted, I will be writing more about this later this week.
The March inflation report
The Consumer Price Index for All Urban Consumers rose 0.1% in March on a seasonally adjusted basis, the U.S. Bureau of Labor Statistics reported today. Over the last 12 months, the all-items index increased 5.0%. Both of those numbers were below consensus estimates, and the year-over-year increase of 5.0% was the smallest since the period ending May 2021.
Core inflation, however, matched expectations with an increase of 0.4% in March and 5.6% year over year. So this inflation report was a mixed bag.
A key factor in moderating all-items inflation was a 4.6% decrease in the price of gasoline, now down 17.4% year over year. On the other side of the equation, shelter costs were up 0.6% and rose 8.2% over the last year. More numbers:
- The costs of food at home fell 0.3% for the month, a welcome break after months of raging price increases. It was the first decline in that index since September 2020. Food at home costs are now up 8.4% year over year.
- The medical care index fell 0.5% for the month and was up only 1% year over year.
- Costs of used cars and trucks fell 0.9% and are down 11.2% year over year.
- New vehicle costs rose 0.4% and are up 6.1% for the year.
- Apparel costs rose 0.3% and are up 3.3% for the year.
I’d say this was a fairly positive inflation report, given that shelter costs are a lagging indicator and should be declining in future months. But gasoline costs are notoriously volatile, so we can’t expect that downward trend to continue.
Here is the one-year trend for all-items and core inflation, showing that while overall inflation has been declining, core inflation remains stubbornly above 5.5%. The March report marks the first time in over two years that core inflation came in above all-items.
What this means for TIPS
Investors in Treasury Inflation-Protected Securities are also interested in non-seasonally adjusted inflation, which is used to adjust principal balances on TIPS. For March, the BLS set the inflation index at 301.836, an increase of 0.33% for the month. This means that principal balances for all TIPS will increase 0.33% in May, following a 0.56% increase in April.
For the year ending in May, TIPS principal balances will have increased 5.0%. Here are the new May Inflation Indexes for all TIPS.
What this means for future interest rates
Today’s report sends mixed messages. The Federal Reserve can certainly celebrate a dramatic fall in annual all-items inflation, from 6.0% in February to 5.0% in March. But core inflation — considered a more accurate measure — actually rose in March, from 5.5% to 5.6%.
Will the Federal Reserve view this March inflation report as the “positive news” it needs to call a halt to future increases in the federal funds rate? I doubt it. I think we have at least one more 25-basis-point rate increase to go, which would put the short-term rate in the range of 5.0% to 5.25%, finally slightly above the annual U.S. inflation rate.
From this morning’s Bloomberg report:
“May should still tilt to a hike,” said Derek Tang, an economist at LH Meyer/Monetary Policy Analytics in Washington. “But it does take some of the wind out of whether another hike in June will be needed at all.”
• I Bonds: A not-so-simple buying guide for 2023
• Confused by I Bonds? Read my Q&A on I Bonds
• Let’s ‘try’ to clarify how an I Bond’s interest is calculated
• Inflation and I Bonds: Track the variable rate changes
• I Bonds: Here’s a simple way to track current value
• I Bond Manifesto: How this investment can work as an emergency fund
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David Enna is a financial journalist, not a financial adviser. He is not selling or profiting from any investment discussed. I Bonds and TIPS are not “get rich” investments; they are best used for capital preservation and inflation protection. They can be purchased through the Treasury or other providers without fees, commissions or carrying charges. Please do your own research before investing.



























REALLY appreciate the wisdom in this online community! Thank you, Dave!