Deductions & credits

What I am asking is clarification on the 2nd part of the question, unearned income? I only receive SSDI so I have no earned income, but this year  if my social security is counted for half of my unearned support , it is close.  I have heard it both ways , So say I pay more than half my support this year while her income has been in the toilet, what then? Does that make sense.