From what my wife said, there is no interest. Just a way of forcing yourself to save as part of a group. Gives one an incentive not to spend it immediately you get it. She explained that in her mother's group, people elect a month when they get a payout....it could be December for Xmas or in a month when you intend to go on vacation or to save for the special present that you mean to get someone.......from what she says it can work but I can also see how it can fail......that's why it depends on the group that you are a part of................apparently....