An annuity can guarantee any or all of the following:
Immediate annuities are exempt; they need no guarantee because there is no accumulation period for generating interest.
As for deferred annuities: fixed annuities accrue interest at a guaranteed rate for at least a certain duration; indexed annuities and variable annuities offer low guarantees but provide better returns if market factors allow.
Get further detail about annuities with guaranteed interest.
The size of your pension payments is not set until you initiate your annuity's income phase because the longer you save, the larger your pension payments will be. However, once your income phase begins, the size of your pension payments is guaranteed.
Get further detail about annuities with guaranteed income.
Besides that, you can receive various guarantees pertaining to the duration of your pension (see below).
Traditionally, annuities continue to pay a constant stream of income for as long as the annuitant lives. However, there are alternatives which enable you to guarantee or partially guarantee the duration of your pension for a fixed number of years. There are even combinations of these two types of guarantees available to you.
Get further detail on annuities with guaranteed duration.