The Child Maintenance and Enforcement Commission is responsible for the child maintenance system. I have asked the Child Maintenance Commissioner to write to the hon. Member with the information requested and I have seen the response.
Letter from Stephen Geraghty:
In reply to your recent Parliamentary Question about the Child Support Agency, the Secretary of State promised a substantive reply from the Child Maintenance Commissioner as the Child Support Agency is now the responsibility of the Child Maintenance and Enforcement Commission.
You asked the Secretary of State for Work and Pensions, how many residents of Bassetlaw constituency have child maintenance arrears of six months or more outstanding from (a) the Child Support Agency and (b) the Child Maintenance Enforcement Commission. 
The Child Maintenance and Enforcement Commission took responsibility for the Child Support Agency from the Department for Work and Pension on 1 November 2008. The Child Support Agency continues to operate the current maintenance schemes until the Commission introduces the future maintenance scheme set out in the Child Maintenance and other Payments Act 2008. The future scheme is currently planned to be introduced in 2011.
Information relating to child maintenance payments by parliamentary constituency is regularly published in the Child Support Agency Quarterly Summary of Statistics, the latest version of which is available online at the following link:
Information on the number of parents who have child maintenance arrears outstanding is only available for cases on the current child maintenance scheme, introduced in 2003. The Commission estimates that at the end of June 2009 there were a total of 1,020 non-resident parents in Bassetlaw parliamentary constituency with six months or more child maintenance arrears outstanding.
I hope you find this answer helpful.