The average income of a self-published author can vary greatly depending on a number of factors, such as the quality of their work, how well they promotion and market their book, and luck. That said, many self-published authors make very little money from their work. A recent survey of over 5,000 self-published authors found that the median annual income from writing was just $3,120, with 43% of authors making less than $500 per year.