I bond interest is calculated using so-called composite rates based on a fixed interest rate and an inflation-adjusted rate, which we describe in depth below. You can purchase another $5,000 with your tax refund, upping the annual total purchase amount of series I bonds to $15,000 per person. Investors can buy up to $10,000 worth of I bonds annually through the government’s TreasuryDirect website. In addition, series I bonds are exempt from state and local income taxes, which makes them an even better low-risk investment for investors who live in high-tax states and cities. Interest rates on I bonds are adjusted regularly to keep pace with rising prices. Treasury to protect your money from losing value due to inflation. I bonds are safe investments issued by the U.S. “Today’s I bond yield far surpasses that of any other government-guaranteed interest rate available from any bank, brokerage or other insured source,” says Steven Jon Kaplan, CEO at True Contrarian Investments in Kearny, N.J. With inflation rates hitting highs not seen since 2007, investors are becoming more interested in higher-returning, lower-risk investments, and this variety of savings bond fits the bill. savings bond designed to protect the value of your cash from inflation.