Is there a form or a way to keep the irs from holding my tax return? I’m owed back child support from the non custodial parent and he waits until the last day to file his taxes and it’s not

I'm not sure about the question you're asking.  Why do you think the IRS would hold your return if you are owed back child support?

If you are referring to the delay in processing returns that contain the Earned Income Tax Credit or the Additional Tax Credit, there is no form you can file to hurry up the process. By law, he IRS can’t issue your refund before February 15, and this year they state:

If you claimed the Earned Income Tax Credit (EITC) or the Additional Child Tax Credit (ACTC), you can expect to get your refund as soon as the first week of March if:

• You file your return online
• You choose to get your refund by direct deposit
• We found no issues with your return

For more information see this article on the IRS website:  When to Expect Your Refund if You Claimed the Earned Income Tax Credit or Additional Child Tax Credit