Csa payments, where do they go?

Jetlag2017

Around 2006 my partner and I seperated for around 18 months, it was a difficult time and I involved CSA. He did not pay any money to them during that period. Fast forward to now and we have been back together for the last 8 years. They have been collecting arrears of around £4000 from him for the last few years. My query is, where is this money actually going? When he questioned them on this, he was told that during the time I received benefits while seperated this money was to contribute towards those costs.
Hoping someone can advise.

WYSPECIAL

Sounds like the money is owed to the Secretary of State. If he had paid it at the time you wouldn't have got all of it. It would have been used to pay for some of the benefits you were receiving.

If this is the case the money you are now paying is going to the government.