Sadly this case of non payment isn't unusual.

The easiest way to deal with child maintenance is to check what the amount should be by reference to the child maintenance service ("CMS") calculator.  

Providing both parents are satisfied the calculation is correction, most then agree the figure and that is the sum paid each month by the non resident parent. 

If you experience difficulties in getting your ex to pay child maintenance though, it can become more complicated and the sooner you make an application to the CMS for an assessment, the better; As you can only claim back-dated child maintenance from the date you applied to the CMS.

If you've any queries about child maintenance payments or the CMS, please get in touch.