Subject: Re: Portfolio for a 90 year old
Much better is to buy TIPS with a term ending when you want the annuity payments to start ...

This is an interesting concept. You get to keep up with inflation plus a bit over the term. The only issue I can think of is that TIPS throw off some phantom income each year until you dispose of them and begin some sort of immediate annuity. That means there will be a tax expense each year that has to be accounted for.

Another issue may be if the end date happens to coincide with an artificial zero interest rate period. In that case, an immediate annuity may pay less than expected, while inflation is still higher than the interest rate.