Do I report my kid's business income on my tax return?

Generally no, and this surprises people who assume a dependent's money flows onto the parent's return automatically.

A child's earned income belongs on the child's own return. If your kid crossed the $400 net self-employment threshold, they file, in their own name, with their own Social Security number. You can help them do it, and plenty of fourteen year olds have no idea they have a filing obligation until somebody explains it, but the return is theirs.

The exception involves unearned income rather than earned. There is a provision that lets a parent elect to report a child's interest and dividends on their own return in certain circumstances. That is about investment income, not about a lawn business, and it does not apply to money a kid earned by doing work.

Claiming them as a dependent is a separate question and usually unaffected. A kid can be claimed as a dependent and still file their own return. The two things run in parallel and the dependency status generally survives a kid earning money, as long as the other requirements are met.

What the kid's return looks like at this scale is less intimidating than it sounds. A Schedule C reporting what came in and what went out, and a Schedule SE calculating self-employment tax. If the record keeping has been happening all year, it is an afternoon. If it has not, it is a reconstruction, which is the actual argument for the notebook.

Worth saying out loud to your kid: filing is not a punishment for making money. It is the thing that turns informal cash into documented earned income, and documented earned income is what makes a Roth IRA possible.

This is a starting point rather than a ruling. Rules change and vary by state, and none of this is tax advice. An accountant will answer this specific question quickly.