Thousands of teenagers are missing out on savings that were invested on the day they were born, the government has said.
The warning comes from HMRC which says the average Child Trust Fund (CTF) has £1,500 in it.
It is now one year since the first account holders started turning 18 and around 55,000 CTFs mature every month.
This means their owners can withdraw funds or transfer savings into an adult ISA.
HMRC said hundreds of thousands of accounts have been claimed so far, but many have not, amounting to £9billion collectively.
CTFs were set up for all children born between 1 September 2002 and 2 January 2011 with a live Child Benefit claim.
Parents or guardians set up these accounts with Child Trust Fund Providers – usually banks, building societies or investment managers – using vouchers provided by the government.
Have you searched and found a forgotten account? Get in touch: emma.munbodh@mirror.co.uk
If an account was not opened by the child’s parent, HMRC set one up on the child’s behalf.
Between 2002 and early 2011, about six million CTFs were opened by parents or guardians, with a further million set up by HMRC.
Economic secretary to the Treasury, John Glen, said: “If you’re unsure if you have an account or where it may be, it’s easy to get help from HMRC to track down your provider online.”
What is a child trust fund?
Under the scheme, parents and guardians with kids born between 2002 and 2011 received a voucher to deposit into a CTF account on behalf of their child.
Vouchers were worth between £50 and £1,000 depending on when children were born, as well as whether parents were on a low income at the time.
These needed to be invested in special CTF accounts provided by a variety of banks and investment companies, with parents choosing between a cash or stock and shares version.
Where parents failed to deposit vouchers, HMRC will have done so for them.
At 16 years, a child can choose to operate their CTF account or have their parent or guardian continue to look after it, but they cannot withdraw the funds. At 18 years of age, the CTF account matures and the child is able to withdraw money from the fund or move it to a different savings account.
How much was put in?
The government initially put £250 into a tax-free account when the child was born, then added another £250 when he or she reached the age of seven.
For lower-income families, the payment was £500.
Parents, family and friends could also contribute to the account, up to set limits.
How much is in them now all depends on what the government put in in the first place, whether your parents added to it and any gains you’ve accumulated over the years.
Have I got a lost account?
Any young people unsure about whether or not they have a CTF should first ask a parent or guardian if they remember setting one up.
Once they know who their provider is, they should contact them directly – and either request to withdraw the money or transfer the funds into an adult ISA or other savings account.
You can use this online tool to check if you have a forgotten account.
The Share Foundation charity also runs a free finding service.
More information on child trust funds is available on through the government-backed Money and Pensions Service.