When liability for child support ends
A very quick note on NG v Secretary of State for Work and Pensions & Anor (Child support : receipt of benefit) (CSM)  UKUT 20 AAC (15 January 2015), which concerned the issue of the correct date on which liability to pay child support ends.
Liability of course ends when the child ceases to be a 'qualifying child' under section 55 of the Child Support Act 1991. Essentially, they remain a child if they are under the age of 16, or if they are under 19 and receiving full-time education. However, they may also remain a child if those conditions are not met but child benefit continues to be payable for them: paragraph 1A of Schedule 1 to the Child Support (Maintenance Calculation Procedure) Regulations 2000, as amended by regulation 4(2) of the Child Support (Miscellaneous Amendments) (No 2) Regulations 2009. In other words, liability then ends when the child benefit is no longer payable.
The point decided by NG is that 'payable' means 'properly or lawfully payable'. Accordingly, it must be considered whether the child benefit was properly or lawfully payable, not simply whether it was actually paid. In NG the Tribunal only considered whether the child benefit was actually paid, and therefore the case was remitted to be re-heard by a different Tribunal.
As to when child benefit ceases to be payable, see here.