From 12th April 2010 any income that you receive from child maintenance payments is not included as income when calculating tax credits or when calculating benefits. You do not need to include such income anywhere in the calculator after this date.
Before April 2010 child maintenance payments were included when Income Support and other out-of-work benefits were calculated but with a disregard of the first £20 a week received. A full disregard of income from child maintenance payments has applied in Housing Benefit and Council Tax Benefit since November 2009.
Note that spousal maintenance payments - payments that are not for children - are not included in this category and should be entered under ‘other income’ (if you are under age 60).