If I only qualify for the foreign earned income exclusion for part of the year, how does that work?

The Foreign Earned Income Exclusion is prorated based on the number of qualifying days you meet either the bona fide residence test or the physical presence test. If you moved abroad partway through the year, or moved back to the U.S., you multiply the annual maximum exclusion, which the IRS adjusts yearly for inflation, by the fraction of the year you qualified. For the physical presence test you need 330 full days in a foreign country during any rolling 12-month period, so a partial year may still qualify if your 12-month window straddles two tax years. Only foreign earned income, meaning wages or self-employment income for services performed abroad, is eligible; passive income like dividends never is. File Form 2555 to claim it. See irs.gov for the current annual exclusion amount.