FRA: is Full Retirement Age. Assume Spouse A at FRA - 66-67 entitled to $3000 per month. Spouse B at FRA on OWN earnings is entitled to $1600. The fifty percent is meaningless - $1600 is more than half of spouse A. If spouse A delays to 70..... the 8% per year at age 70 is $3720-$3960. The Spouse B fifty percent will always be the FRA or $1500 and totally meaningless based on this scenario. Assume both are at FRA: Spouse A or Spouse B will upon death of other get the $3720-$3960 -- again based on year born. KEEP IN MIND: Spouse A decides to wait to 70 and passes at 68. Spouse B will not benefit in anyway to wait for deceased Spouse A's 70th but will get the 8% to the age 68 for calculation purpose. Spouse B needs to apply for deceased Spouse's benefit upon death of Spouse A.