Carmen and Carlos, who have filed joint tax returns for several years, separated this year. Carlos works in construction and is often paid in cash. Carlos says he only worked a few weeks this year and made $11,000. In prior years he made approximately $35,000 per year, and Carmen is surprised that his income is so low this year. Carmen received a salary of $38,000 as a medical laboratory technician. They have no dependents and claim the standard deduction. What tax issues should Carmen and Carlos consider?