Bonus adjectives are listed in this post. Each word below can often be found in front of the noun bonus in the same sentence. This reference page can help answer the question what are some adjectives commonly used for describing BONUS.
added, additional, annual, average, big, dollar
double, end, est, extra, fat, financial
free, generous, good, great, handsome, huge
incentive, large, little, major, new, nice
quam, quandoque, real, small, special, substantial
unexpected, vir, welcome, year, yearly
Hope this word list had the adjective used with bonus you were looking for. Additional describing words / adjectives that describe / adjectives of various nouns can be found in the other pages on this website.