You have to keep good records of any purchases you make through these plans because the dividends are considered taxable income even if you reinvest them. In addition, when you sell your shares, you need records showing how much you paid for your shares so you can calculate how much money you made (called capital gains) for tax purposes. Its likely that if you are a Teenvestor under 14 years old, you’d probably owe no taxes whereas if you are over 14 years of age you may have to pay taxes on dividends and on profits when you sell your shares.