HMRC issues National Insurance Numbers to most young people just before their 16th birthday.
If a child has been part of a claim, but is not part of a claim when they are 15 years, 9 months old, HMRC can be contacted to request a NINo. This process takes approximately 15 working days.
If a child has never been part of a Child Benefit claim (or a claim for a childcare service administered by HMRC) HMRC will have no record of them. An online application can be made to the Department for Work and Pensions to obtain a NINo. HMRC does not collate information on the number of young people who cannot be included in the automatic process.