I need to file my child income form (under 24 college student) but my parent did not file their taxes

If you are subject to kiddie tax and your parents haven't filed their tax return yet, you have two choices.

The best approach is to wait until your parents have filed their tax return, or at least finished preparing it. File an extension if you will not be able to file by May 17. The extension gives you until October 15 to file, but if you will have a payment due on your tax return, you have to pay the tax by May 17, even though you don't have to file the return until October 15.

The alternative is to use "reasonable estimates" of your parents' tax return information, but then you have to file an amended return, Form 1040-X, with the final amounts after they have finished their tax return. And in TurboTax Online there is no way to indicate that you are using estimates. It can only be done in forms mode in the CD/Download TurboTax software.

The following is from the IRS instructions for Form 8615.

Incomplete Information for Filing

If the parent's taxable income, filing status, or net unearned income of the parent's other children isn't known by the due date of the child’s return, reasonable estimates can be used. Enter “Estimated” next to the appropriate line(s) of Form 8615. When the correct information is available, file Form 1040-X, Amended U.S. Individual Income Tax Return.

Instead of using estimates, the child can get an automatic 6-month extension of time to file. For details, see Form 4868, Application for Automatic Extension of Time To File U.S. Individual Income Tax Return.

CAUTION: An extension of time to file isn’t an extension of time to pay.