Yes, an I bond stops paying interest after 30 years. And I have an old one coming up soon, so I’d better make note of that. By the way, here’s a chart that shows what a particular I bond is paying, based on when it was bought. The chart is at the bottom.
https://www.treasurydirect.gov/indiv/research/indepth/ibonds/res_ibonds_iratesandterms.htm#now
So at this juncture if I have some I-bonds that are like 20 years since issue, might I be better holding them than cashing them in today ?
Is there a web tool to see what is happening to their value month to month right now ?