You will need two things: The estimated " gross " monthly amount of your pension from your government job not covered by Social Security . and The estimated monthly amount of your Social Security benefit as a spouse , widow , or widower before the effect of GPO .
How do I know what my spouse's benefit will be if I retire at full retirement age?
If your spouse already receives benefits  ask them what their benefit would be if it started at their full or normal retirement age . Divide this amount in half and round down to the nearest dollar .This is your estimated spouse 's benefit if you retire at full retirement age .
Another question for you regarding Medicare alone. Do I need to apply online?