Definition of 'main carer' for child in separation and divorce

[chancer2014]

Is the definition of 'main carer' for a child the person who received child benefit or the person who does most childcare? And does this affect arguments over who is the Residency parent?

There is no such thing as residency anymore and the answer to your question will vary depending on the context. In terms of who the child live with or spends time with, the main carer will be the person who did the day to day care. In terms of tax credits, they default to the holder of child benefit as far as I am aware but this can be challenged.