In a variable annuity, what remains fixed once payments begin?

In a variable annuity, once payments begin, the number of annuity units credited remains fixed. This is because the number of units is established at the time the annuitization occurs, based on the investment performance prior to the payment phase. Once the monthly payouts commence, the actual number of annuity units does not change, even though the value of each unit can fluctuate based on the underlying investments.

The value of the annuity units is variable and can change as it is tied directly to the performance of the underlying assets within the annuity. This variability means that the monthly payment amount can also change over time, as it is determined by the current value of those annuity units times the fixed number of units credited. The total investment amount, while significant for accounting purposes, does not have a fixed status once payments commence, as it does not directly relate to the ongoing mechanics of payment calculations in a variable annuity.