They can also be very harmful on strategies about when to start SS.  I worked that out carefully for a friend/client, taking into account his other income and his wife's retirement planning.  He wanted the checks to start in July, and not sooner.  It was an ordeal to convince them not to backdate them to January.  He was smart enough to know that starting the payments earlier would lower the amount he received for life, while increasing his Medicare premiums by 50% in the current year.  Most people would just look at the lump-sum check as a windfall.  

Another client who is 68 and should have started collecting earlier, just told me he plans to apply in January so he'll get the 6% COLA.  I told him I'm not sure, but I think the COLA only goes to those who have started receiving checks by December.  Tried looking it up, and couldn't find an answer.  Does anyone know?