In a TIAA Traditional account one "buys" the guaranteed income for life with periodic payments rather than with a "lump sum", and one also can determine when the guaranteed income should begin. Why would this not be a better procedure than DIA?For both DIAs and SPIAs, a lump-sum premium is paid today in return for a guaranteed income for life. The difference is that for the DIA, the guaranteed income does not begin until a later date.
Dick