what is Community Property Addition Adjustment?

[MaryK4]

If you are filing separate returns and have Community property, the community property addition adjustment is the amount that you would add to the spouse with the lower income to make the community income equal.  For example, if Bill had $9 income and Beth had $21, they would each report $15 (one half).  Bill would need an addition adjustment of $6 so he would have the $15, Beth would have the corresponding $6 subtraction adjustment so she would have $15.