If their parents do no claim Child Benefit, then children born since 2013 may miss out on automatically receiving a national insurance (NI) number that entitles them to work and study in the UK.
Currently, British-born children are automatically sent NI numbers by the government when they turn 15 years and nine months old. Virtually all migrant workers, by contrast, need to apply for NI numbers and attend an interview.
A quirk in the system means the vital numbers are sent only to children whose parents registered for child benefit for that child.
The income limit of £50,000 has also led to thousands of parents failing to claim the benefit.
The number of registrations has dropped by 516,000 since 2013, when the tax charge on high-earning families came in. Those children who never receive child benefit could be forced to prove their identity to qualify for a national insurance number.
What is Child Benefit worth?
Child benefit, which pays £20.70 a week for a first child and £13.70 for each additional child. The benefit is repayable if a parent or their partner earns more than £50,000. On earnings above £60,000, the payment is completely wiped out by an extra tax charge.
Parents earning more than £60,000 can register for child benefit but not claim it. This avoids the tax charge but ensures the parents and the child keep their national insurance entitlements.
It is yet another confusing quirk in the child benefit system, which already leaves stay-at-home mothers and fathers worse off.
“Unless the system has changed, there will be a whole raft of children without NI numbers by 2029”.
Why a NI number is vital
It is possible that some of the 516,000 families who have de-registered for child benefit did have their children on the system at some point. This means that they will still get an NI number, but if a child has never been registered then they will not be sent one automatically. These youngsters will have to apply alongside the more than 620,000 immigrants who apply for national insurance numbers a year, according to Department for Work and Pensions (DWP) figures.
It is essential to have an NI number to get a job as well as to apply for a student loan. They are also needed by pension and Isa providers, as well as local councils for claiming housing benefit and by the DWP for claiming any state benefits.
You are likely to need to provide your NI Number to banks, lenders and credit card companies if you try to open an account.
The DWP have said children who have not automatically received an NI number can apply once they have reached 16. They also advise those who are aged 16-20 with no NI number to call the helpline on 0300 200 3500, while anyone aged over 20 should contact the national insurance application line on 0800 141 2075.
Any migrant who wants to work and study in Britain must apply for an NI number at their local job centre and attend an interview. Although it is unlikely British-born applicants would need to go through this process, if they could prove they had the right to work in the UK.
Get the best of both worlds
By careful planning, a parent can claim Child Benefit and avoid the High Income Child Benefit Charge.
The trick is to know the difference between "claiming" a benefit and "receiving" it.
You should always claim Child Benefit, but if you are a higher earner, you may opt not to receive the money. This does not stop you getting the NI Credit, which can be vital for the level of pension you receive when you retire.
Much more information is available here.