How can I file to get the stimulus for my kids that their father that owes child support

https://www.irs.gov/coronavirus/economic-impact-payments

You cannot file a return or check on the status of a stimulus payment on behalf of another person for the reason that they owe you back child support unless they specifically authorize you to do so.  

 

It is also possible that he did receive the stimulus.  If he wants you to look into it, he would have to give you permission to speak to the IRS.  He can do this by filling out a POA that authorizes you to speak to the IRS on his behalf or by any of the other methods listed below.  

 

 

"Here are different types of third-party authorizations:

• Power of Attorney – Allows someone to represent a taxpayer in tax matters before the IRS. With this authorization, the representative must be an individual authorized to practice before the IRS.
• Tax Information Authorization – Appoints a person to review or receive a taxpayer's confidential tax information for the type of tax for a specified period.
• Third Party Designee – Designates a person on the taxpayer's tax form to discuss that specific tax return and tax year with the IRS.
• Oral Disclosure – Authorizes the IRS to disclose the taxpayer's tax info to a person the taxpayer brings into a phone call or meeting with the IRS about a specific tax issue."