Series I bonds rate could top 5% in November. Here’s what to know before buying more

The annual rate for newly bought Series I bonds could top 5% in November — and there are several things to consider before adding more to your portfolio, experts say.  

November’s rate for new purchases could be higher than the current 4.3% interest on I bonds bought through Oct. 31, leaving some investors wondering about whether to buy more.

“It’s definitely worth it to wait until November” to decide, said Ken Tumin, founder and editor of DepositAccounts.com, which tracks I bonds, among other assets.

The U.S. Department of the Treasury updates I bond rates every May and November and there are two parts to I bond yields: a variable and fixed portion.

The variable rate adjusts every six months based on inflation and the Treasury can also change the fixed rate or keep it the same. (The fixed rate stays the same for investors after purchase, and the variable rate adjusts every six months based on the investor’s purchase date.)  

Based on inflation, the variable rate in November will likely increase to 3.94% from 3.38%. But the current 0.9% fixed rate could also increase, based on yields from 10-year Treasury inflation-protected securities, or TIPS, according to David Enna, founder of Tipswatch.com, a website that tracks I bond rates and TIPS.

Higher fixed interest could be attractive to longer-term investors, experts say. But they’d need to purchase new I bonds between Nov. 1 and April 30 to score the increased fixed rate.

While I bonds remain an attractive option for long-term investors, the choice may be harder for shorter-term goals, experts say.

One of the downsides of newly purchased I bonds is you can’t access the money for at least one year and you’ll lose three months’ interest by tapping the money within five years. 

However, there are other competitive options for cash with more liquidity, such as high-yield savings accounts, certificates of deposit, Treasury bills or money market funds.

Meanwhile, one-month to one-year Treasury bills are offering well above 5%, as of Oct. 16, and the biggest money market funds are paying interest in a similar range, according to Crane data.