Thank you for being patient with me:)
The issue is about how to deduct loss carried over from a previous year. If husband's capital gain loss of $3000 carry over from 2017 can be deducted in 2018 from community income. If in 2018 husband earned $0, but wife earned $50,000. Both incomes added together are community income.
(The numbers are just to understand the concept. Some people had questions about it.)
