The 16-year-old singing sensation is worth an estimated $100 million but has a cap placed on his spending and is forced to go without if he reaches the top of his budget too soon.
He admitted: "My money is being invested. I only have a credit card, which allows me to spend a certain amount of money everymonth. If I reach the limit after the first week, I won`t be able to buy any more stuff until the month is over. My mom is in control of that."
Despite the tight control placed on his finances, Justin insists he doesn`t mind because he is more interested in his career than the financial rewards it brings.
He told Switzerland`s Blick newspaper: "It`s not that money wouldn`t mean anything at all to me. But the main thing is to do what my passion is. And that`s music. It`s nice to get paid for that, though. Performing feels natural to me, just like walking."
As well as controlling his finances, the `Baby` hitmaker`s mother, Patti Mallette, also keeps a close eye on the fan mail the young star receives.
Asked about having underwear thrown at him on stage, he said: "My Mom doesn`t like it when that happens. Sometimes they have phone numbers written on them. I don`t know what happens to them."