Do I have to file a state return if I filed a nonfiler form?
Generally, many states require that you file a state tax return in addition to a federal tax return. If you complete a nonfiler form (like GetCTC or a nonfiler portal with the IRS)then you might not have to file a state return, but state laws vary so you should double check your state rules.
Many states have their own tax credits similar to the Earned Income Tax Credit (EITC), Child Tax Credit (CTC), and heat and rent rebates. It is easiest to file your state tax return at the same time as your federal tax return if you can. You can find state specific instructions and resources at your state's Department of Revenue website.