<<So it looks like the October buyers (including me to some extent) of I-bonds may get 0% for 6 months, but what will the November buyers get?>>

The same thing, but they'll be a month behind.

When you purchase an I Bond, regardless of the month you buy it in, you receive the current combined annualized rate (fixed + inflation component) for 6 months. After that, you receive the next inflation adjustment, added to your fixed rate (which remains fixed for as long as you own the bond), for the following 6 months, and so on.

So the October buyers get 1% + 5.75% (approx) for Oct - Mar, and then they would (currently) get 0% for Apr - Sep. The November buyers get exactly the same, but for Nov - Apr followed by May - Oct. Clear?

I see.

Since the value of an I Bond can never go down, in this case -2% + 1% = 0%. Pity the poor folks who have a 2% or higher fixed rate. They'll actually be losing more than those with the 1%'ers. (Yeah, I know, no solace whatsoever.)

Is it true that an I-bond can never go down per 6 month period, or is it overall from the date of purchase? If one has older I-bonds that have earned X%, then a certain 6 month period has a -2% variable component and a 1% fixed component. Does the bond have total earnings of X% at that point or X-1%?

If the I-bond is redeemed at that point, does it receive X% or X-1%?

If the I-bond is still within the 5 year window, which 3 months of earnings are forfeited, is it the last 3 months (of 0%, or effectively no forfeit at all), or some other 3 month period?

I think I have heard that TIPS calculate the "deflation" case differently. How is it calculated for TIPS? Can a negative yield actually be accumulated?

And finally, does anyone believe that inflation will remain at -2% for this period even with gasoline prices on the rise again? Does CPI-U even include energy?