By David Enna, Tipswatch.com
U.S. annual inflation continued on a downward trend in August, falling from 2.9% in July to 2.5%, the lowest annual rate in 3 1/2 years.
For the month, seasonally-adjusted inflation rose 0.2%, the Bureau of Labor Statistics reported, which matched expectations. But the annual number was below expectations of 2.6%. Core inflation, which removes food and energy, rose 0.3% for the month (slightly higher than expectations) and held steady at 3.2% for the year.
Once again, shelter costs were the trouble-maker in this inflation report. The index for shelter rose 0.5% in August and was up 5.2% year-over-year. The BLS called shelter “the main factor” in the increase in all-items inflation. Also in the report:
- Gasoline prices fell 0.6% for the month and are down 10.3% year-over-year.
- The costs of food at home increased just 0.1% and are up 2.1% for the year.
- Apparel costs rose 0.3% and were also up 0.3% for the year.
- The costs of medical care services fell 0.1% for the month but are up 3.2% for the year.
- Costs of used cars and trucks fell 1.0% (the third monthly decline in a row) and are down 10.4% for the year.
- Costs of new vehicles held steady and are down 1.2% for the year.
- Motor vehicle insurance costs increased 0.6% for the month and are up a lofty 16.5% over the last year.
- Airline fares rose 3.9% for the month, after declining five months in a row.
So this report, overall, shows a positive trend of declining U.S. inflation, with the annual rate dropping to its lowest level since February 2021. Inflation watchers know that 2.5% for CPI-U is entering a normal historical range. Here is the trend in U.S. inflation over the last 12 months, showing the sharp decline in all-items inflation, despite lingering high costs of shelter:

What this means for TIPS and I Bonds
Investors in Treasury Inflation-Protected Securities and U.S. Series I Bonds are also interested in non-seasonally adjusted inflation, which is used to adjust principal balances on TIPS and set future interest rates for I Bonds. For August, the BLS set the CPI-U inflation index at 314.796, an increase of 0.08% over the July number.
For TIPS. Today’s report means that principal balances for all TIPS will increase 0.08% in October, after rising 0.12% in September. Here are the new October Inflation Indexes for all TIPS.
For I Bonds. The August inflation report is the fifth of a six-month string that will determine the I Bond’s new variable rate, which will be reset on November 1 and eventually roll into effect for all I Bonds. After five months, inflation has increased 0.79%, which would translate to a variable rate of 1.58%, down from the current 2.96%.

One month remains, so we could be looking at a variable rate in the range of 1.78% to 1.98%, which would disappoint I Bond investors. But that’s the trend in inflation over the last half year. And September’s rate is not likely to bump higher, given the current trend in gasoline prices:

I Bonds, in my opinion, remain attractive with the current fixed rate of 1.3%, which remains in place for the potential 30 years to maturity. But older I Bonds with fixed rates of 0.0% to 0.2% are likely to deliver weak returns for six months.
What this means for Social Security COLA
The Social Security Administration uses a different inflation index — CPI-W — to determine the next year’s cost-of-living-adjustment. And it looks only at the average of three months of data, from July to September, compared with the average for the same three months of the previous year. For August 2024, the BLS set the CPI-W index at 308.640, an increase of 2.4% over the last year.
Here is the current trend, with a COLA of 2.4% looking increasingly likely:

What this means for future interest rates
The August inflation report is good news for the Federal Reserve, even though shelter costs remain a nagging sore point and monthly core inflation was a tick higher than expectations. Annual CPI-U has fallen to 2.5%, and the Fed’s preferred index, Personal Consumption Expenditures, is also trending lower.
The Fed’s Open Market Committee will meet next week and we can be nearly 100% certain that meeting will result in a cut in short-term interest rates. I would guess 25 basis points, because I believe the Fed will want to act cautiously. There is little evidence that the U.S. economy, while slowing, is heading toward a steep decline.
This morning’s Wall Street Journal report includes the subhead: “CPI data tees up Fed to begin gradually cutting rates next week.” That’s on target.
• 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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• Now is an ideal time to build a TIPS ladder
• Confused by TIPS? Read my Q&A on TIPS
• TIPS in depth: Understand the language
• TIPS on the secondary market: Things to consider
• TIPS investor: Don’t over-think the threat of deflation
• Upcoming schedule of TIPS auctions
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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.











Interesting question, and it raises many issues, which I may write about later this week. My TIPS ladder ends in…