How do I enter my parents income since they haven't filed yet?

You are most likely being asked about your parent's income because you are being subject to "kiddie tax" on Form 8615. Usually, this means that you have more than $2,200 of investment or unearned income, which is then taxed at your parent's tax rate. Per the IRS, 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.

Form 8615, Tax for Certain Children Who Have Unearned Income, is required when a child meets all of the following conditions:

1. The child had more than $2,200 of unearned income.
2. The child is required to file a tax return.
3. The child either:
   1. Was under age 18 at the end of 2020,
   2. Was age 18 at the end of 2020 and didn’t have earned income that was more than half of the child's support, or
   3. Was a full-time student at least age 19 and under age 24 at the end of 2020 and didn’t have earned income that was more than half of the child's support.
4. At least one of the child's parents was alive at the end of 2020.
5. The child doesn’t file a joint return for 2020.

Since you will be writing on the pages of the return, you will have to mail in her tax return and will not be able to e-file. When the correct information becomes available, you can file Form 1040-X, Amended U.S. Individual Income Tax Return.

For more information, please see Instructions for Form 8615.