If you click on the retirement account area in your profile, you will see a link to open the retirement account settings and assumptions. There you can specify the age at which smooth withdrawals begin and end. If you begin smooth withdrawals past age 72, you will see that the program imposes Required Minimum Distributions (RMDs) until the age you indicate smooth withdrawals should begin, at which point it will create smooth withdrawals from that point forward based on the remaining balance.