After spiking to 40 year highs in 2021 and 2022 because of the pandemic, inflation had been settling down a bit the last few years. Unfortunately, as a result of the Iran war and its impact on the price of oil (which is integrated into practically everything we buy), inflation has begun rearing its ugly head again. As a result, the Fed is unlikely to be lowering rates anytime soon. Higher rates are bad if you’re a borrower, but they’re great if you’re a saver. With the latest inflation rates, we can now calculate what we think Series I bond rates will be when they reset in November. First, if you’re wondering how Series I bonds work, we explain it all after the rate calculation. We start with what the rate is expected to be when it adjusts in November followed by how Series I bonds work: Table of Contents💸 November 2026 Interest Rate Prediction: 5.41%💸 May 2026 Interest Rate: 4.26%What Are Series I Bonds?Tax ConsiderationsHow Are Interest Rates Calculated?Interest Compounds SemiannuallyHow To Predict Series I Bond Interest RatesWhen Should You Buy Series I Bonds? 🔃 Updated October 2026 with the predicted Series I Savings bond rates for November 2026 now that latest inflation data has been published. The predicted rate for the bonds sold in November will be 5.41% for the first 6 months. 💸 November 2026 Interest Rate Prediction: 5.41% [embed]https://youtube.com/watch?v=Mp8jlHf-c6o&feature=oembed[/embed] With the September inflation figures out from the BLS, we can now predict what the inflation rate will be for Series I bonds issued November 2026 through April 2027. With the March 2026 CPI-U of 330.213 and a September 2026 CPI-U of 336.940, we have a semi-annual inflation rate of 2.04%, which means the inflation-adjusted variable rate will be 4.08% – up from 3.34%. We won’t know what the fixed portion will be until Treasury announces it on November 1st, but as we’ve learned from reading Tipswatch, it tends to track with the 5-year TIPS. Take the average real yield of the 5-year TIPS over the preceding six months and multiply by 0.65. With 5-year real yields averaging right around 2%, that gives us 1.30% – a big jump from 0.90% – and it’s close enough to the line that 1.40% is possible. If we assume a fixed rate of 1.30%, the composite rate would be 5.41%. If it comes in at 1.40%, the composite rate would be 5.51%. As always, you can peek at EyeBonds.info to see how the inflation rate changes impact your specific bonds based on its fixed rate. Should you buy in October? If you buy before November 2026, you get the fixed rate of 0.90% while earning the May-October 2026 variable rate of 3.34% – this means you will be earning at the 4.26% annual rate for six months. Then, after six months, your variable rate will increase to 4.08% and you’ll earn 5.00%. If you wait until November, you’ll earn about 5.41% for the first six months and,