Legal Question in Business Law in California

The important age distinction is not "teenager" per se, but minor vs. adult. If you are 18 or 19, you may steill be a teenager, but in the eyes of the law you are an adult.

If, however, you are 17 or younger, you are a minor, sometimes referred to in old-fashioned law-talk as an "infant."

Since contracts made by minors are more often than not unenforceable, especially if they are contracts made in the course of running a business, it is hugely impractical for an under-18 minor to run a business. Not impossible, but without an adult to sign the contracts and hence be pretty much in charge, minors are greatly handicapped in trying to make deals and conduct business.

I do not know whether minors can be issued business licenses or not.........but running a business without a required license would not be excusable because the operator was a minor and ineligible for the required license. You'd be outta luck there.

As far as taxes go, they impact everyone equally, with a few exceptions, from birth to death. The exceptions mainly involve exemptions for seniors.