Question about my taxes being intercepted?

ok here is my situation. i owe some money to my child support agency but it isnt actually back child support. My son was born and at the time my fiances insurance covered most of the hospital cost except or lke 2500. When me and my fiance split up we were in the cs agencys office and the agent told me i had to pay the rest of the debt off as it was my child also. so anyways i pay like 50 a month on top of my regular support to get that medical bill payed off. Now i am not sure if this is actually concidered "back" child support because my ex has gotten all her checks up to date as far as the support side goes. Last year they intercepted my stimulous check but mailed it back to me from their department. Now would they intercept my tax return this year? I dont see how tis medical dept would be concidered back chid support. Any thoughts please. thanks!