Maintenance problem

I recently received a letter from Child Support saying my ex underpaid me for the first six months of the year because he underestimated his earnings. By $30,000! I then received a letter from Centrelink saying I owe them money because of his underestimation. Fair enough I owe them money because of this but at the rate he decided to pay me back it would take him four years.
I then received two more letters from CSA for 2005 and 2006 saying the same thing. Centrelink are hot on my heels for more money.
I asked CSA to now make his payments collect because I can't keep paying a debt like this that I shouldn't have.
My ex now says he will split his income with his wife so I will only get half the amount of maintenance. He doesn't own his own business so is this possible for him to do with a normal business? He works for a very well known company that owns shopping centres.
Our older daughter will have to change schools if he does this and I will have to move houses.

Hi Rebecca,

I share your frustration! I recently received a letter from Centrelink to say that i owed them money for 2006 and when i inquired i was informed that it was because my ex had under estimated his income. In my case i didn't get any extra $$$ from my ex, yet i still have to pay.

Sorry no good news, as in i wasn't able to change the situation but i thought it may help to know that unfortunately you're not alone.