What should child maintenance cover?

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Name changed for this post.

If parents split and you are entitled to child maintenance what should that money cover?

Mother - has recently become single and struggling alone from a part time job

Father - with a long term partner, good job, decent money and pays just over the CMS calculations and pays for half of child's school lunches/ trips and uniform.

Child is 13 years old and when not at school spends around 60% of time at home with mum and 40% with dad.

Pretty sure maintenance is for everyday living costs. So a roof over their heads, gas/electric, water, food, clothes, shoes.

It’s their contribution to the costs of the child living primarily with the resident parent based on the non resident parent’s income. What the RP wants to spend it on is up to them. With 60/40 contact split maintenance might not be loads as the dad is also funding the costs of the child being with him nearly half the time. He’s also contributing to other school costs which is right but not legally enforceable. Mum could up her hours if she needs more money as a 13 year old doesn’t need childcare and she’ll be getting child benefit and tax credits etc which will help which dad doesn’t get.