I will soon start the process of filling for child support for my daughter who is 5. When she was born her father paid for an DNA test. He was proven to be the father. Since then he has given me $400 by check a month to help care for her. I've asked him for a increase which he won't do. This makes makes over 100,000 a year not including properties he owns. Is there anyway I can look up his tax return information without his social security number. I have his SS number but don't know how and if I can get this information.

No - you cannot get someone else's tax return information. The IRS guards personal data very carefully, for good reason.

Suggest you talk to a lawyer specializing in family law matters to see if it would be wise to sue the father for increased child support.

If you have a court order for child support which he has NOT been paying, you CAN petition, through the federal court system, to have his refund garnished to pay the back child support.

Of course, once he realizes what you are doing, he will adjust his withholdings and estimated tax payments so that he is not DUE a refund, but rather must pay com April 15th. If there is no refund, then it cannot be garnished.

As Ebaines suggested, best you get a lawyer.