A high-income year can send a large share of what you earn to federal and state tax at the top rates. An analysis looks at the whole picture before year-end, while the outcome can still be changed, rather than after the fact.
A business owner in California faced a high ordinary-income year, with income in the Under $1M range for the year. On a conventional approach, the projected combined federal and state tax fell in the $250K–$500K range, a large share of the year's income lost to tax at the top rates.