Can they attach my federaltax refund ?

Depends on who THEY are.

Taking a wild guess that this is over upaid debts and a judgement you have lost... the answer is yes.

If the payment is for a one-time judgement, the tax refund CAN be garnished, but it is rarely done becauise of the time involved in petitioning the federal courts. The process is quite lengthy, and if the IRS issues the refund to the taxpayer before the garnishment action is received, the IRS will NOT trey to get the refund back.

Child support is another matter entirely, because that is a continuing obligation that endures until the child turns 18 years of age.

Once the tax payer becomes aware of the garnishment process, they can defeat it by adjusting their withholdings so they have to PAY instead of getting a refund.