An immediate annuity plan is similar to a single premium insurance plan. You are required to make a single premium payment to kickstart the retirement pension plan and start receiving monthly pay-outs immediately. Deferred annuity pension plans need you to select a premium paying term during which you will make contributions towards the guaranteed pension plan. Under such a pension guaranteed plan, you get to defer the starting date of when you would like to receive pay-outs to a time in the future.