You can apply for Child Benefit at any time after your child is born, but a claim is normally backdated by no more than three months. Applying within three months of the birth can help you receive any entitlement from the earliest available date. Claiming may also protect National Insurance credits for the person caring for a child under 12, even if you choose not to receive the payment because of tax concerns. Check the latest rules and apply through the official GOV.UK Child Benefit page.