Who Is Responsible for Reporting Taxes on a Minor's Investment Account Gains?
An investment account opened for a child years ago has been quietly growing, generating dividends and the occasional capital gain along the way, and it’s only now that the question comes up: whose responsibility is it to actually report any of that on a tax return?
The short answer
Assets in a custodial investment account legally belong to the child, not the parent or whoever opened the account, so any taxable gains, dividends, or interest generated inside it are reported under the child’s own tax identification number. In practice, the custodian — usually a parent — handles the paperwork and filing on the child’s behalf until the child is old enough to manage it themselves, but the tax liability itself sits with the minor.
Why the account is treated as the child’s, not the parent’s
A custodial account is structurally different from a 529 college savings plan in this respect: once money goes into a custodial account, it becomes an irrevocable gift to the child, even though a parent or other adult manages it until the child reaches the age of majority. Because the assets are legally the child’s, any income the account generates — dividends, interest, or realized capital gains from selling investments — is the child’s income for tax purposes, not the custodian’s, regardless of who originally contributed the money.
How the reporting actually happens in practice
- The account carries the child’s tax identification number. Brokerage statements and any tax forms generated by the account are issued under the minor’s own number, not the custodian’s.
- A parent typically files on the child’s behalf. Because most minors don’t file their own returns, the custodian generally handles the process, either including the child’s investment income on the parent’s return when eligible or filing a separate return for the child.
- Rules apply differently once unearned income crosses a certain level. How a minor’s earned income differs from unearned income matters here, since investment gains fall into the unearned category and can be taxed at a different rate than a teen’s own wages once they exceed a certain threshold.
What changes as the account moves or the child grows
Custodial accounts don’t always stay in one place — they can be transferred to a different financial institution as a family’s needs change, though the underlying tax treatment stays tied to the child regardless of which brokerage holds the assets. Many families also start small, using fractional shares as an approachable way to introduce investing concepts, and the same reporting principles apply whether the account holds a handful of fractional shares or a more substantial portfolio. Once the child reaches the age at which the account transfers fully into their control, the responsibility for tax reporting shifts along with it, at which point the now-adult account holder manages both the assets and the associated filing themselves.
Where this leaves you
The custodian does the administrative work, but the tax obligation belongs to the child because the money legally does too. Understanding this distinction helps explain why a parent can’t simply fold a custodial account’s gains into their own return as if the money were theirs, and why families sometimes need to file a separate, simple return for a child whose investment account has grown enough to generate a meaningful tax liability of its own.