www.theguardian.com/money/2018/jul/28/beware-forgoing-child-benefit-could-cost-you-your-state-pension
Not really an AIBU - posting for traffic.
Relevant where one parent is not working and has chosen not to claim CHB (usually this is because the working partner is earning in excess of £60k therefore would have to pay all the CHB back in tax anyway).
"Claiming child benefit, whether it is actually paid or not, ensures the claiming parent receives NICs while the child is under 12. But a mother (and it’s usually the mother) who does not claim, may fail to build up their full state pension entitlement.
To receive a state pension the parent needs to have paid NICs, or received NICs, for a full 35 tax years. The credits are crucial for stay-at-home parents, as they plug the gap in the NICs record while looking after their children."