The answer earlier in the thread put it plainly ...
If Bob made $800 and Mary made $200 the total wages are $1000. One half is income to each spouse- which is $500.
Because Bob made more, he would have a subtraction to get his $800 to $500. Mary would have an addition of $300 to get her to $500.
And IMHO filing separately in a community property state is usually a waste of time and effort.
