The i-bond with a fixed rate of 0% is guaranteed to return less than inflation: Even if you buy their inflation metric as faithful: The 'gains' are taxed. The

The i-bond with a fixed rate of 0% is guaranteed to return less than inflation: Even if you buy their inflation metric as faithful: The 'gains' are taxed. The tax is at income rates, not even LTCG rates. Moreover, what they're attempting to match isn't inflation, it's a specific government inflation metric which contains many corrections which make it obviously not match inflation for the purpose of preserving purchasing power. For example, when inflation goes up the metric assumes that purchasing will shift from high value goods (like steak) to lower value goods (like rice), which causes the metric to read lower. This is no good if your goal is preserving purchasing power: you put in enough to buy steak and the inflation metric is okay with what comes out being only enough to buy a meal of rice (not technically, since steak and rice aren't the only goods but you get my point).