The tax verification form (4506c) is completed one parent at a time.
If you are the first parent listed, please make sure that you sign and select the yellow "finish" button at the top before you try signing for the second parent.
Once you do, the page should re-load and allow you do to the same for the second parent.
If the page does not automatically re-load for you, navigate to another page and return back to Step 3 in your left menu. Clicking the "Begin Signing" button should then allow the second parent to sign and submit.
Please note that if you added the second parent/guardian to your application or made a change to your Guardian information in Step 1 after previously signing the 4506c form, you will not be able to edit. If this is the case, please reach out to us and let us know.