When Are Annuity Units Determined? 
Annuity units are determined after the accumulation phase of the annuity and before the annuitization phase . When the contract becomes annuitized , the accumulation units become annuity units . An actuarial formula is used that takes into account age , sex , payout rate , and assumed interest rate . The number of annuity units and value of each unit is determined at this time , right before starting the annuity payouts . 