supplementary profit
nounUK /ˌsʌplɪˈmentəri ˈprɒfɪt/
US /ˌsʌplɪˈmentəri ˈprɑːfɪt/
Extra money you earn on top of what you already make.
Selling lemonade at the fair gave the family a supplementary profit.
OTHER MEANINGS
2. A small gain added to a company's main earnings from a secondary activity.
The café's supplementary profit came from selling homemade cookies.
3. Money made from a part-time job that adds to a person's regular salary.
Tutoring on weekends became a useful supplementary profit for the teacher.
4. An extra financial benefit gained from recycling or reusing materials.
The school earned a supplementary profit by collecting old newspapers.