HMRC is sounding the alarm for a staggering number of young Britons who may be oblivious to thousands of pounds awaiting them in forgotten Child Trust Fund accounts. Startling new figures from the tax authority reveal that over 670,000 individuals aged between 18 to 22 have yet to claim their funds, with the average account sitting at a tidy £2,212.

Launched in 2005, the Labour-initiated Child Trust Funds were made available to kids born from 1 September 2002 to 2 January 2011, granting £250 or a boosted £500 for lower-income households to kick-start their savings. Parents had the liberty to add as much as £9,000 yearly, with youngsters entitled to tap into the stash as they reach 18.

However, numerous accounts have slipped into obscurity, some forcibly opened by HMRC when parents didn't act within a year post-voucher receipt.

While no new Child Trust Fund accounts can be birthed post-2011, topping up existing ones remains on the table.

Angela MacDonald, HMRC's Second Permanent Secretary and Deputy Chief Executive, is championing the charge to bridge young citizens with their unclaimed money, asserting: "Thousands of Child Trust Fund accounts are sitting unclaimed we want to reunite young people with their money and we're making the process as simple as possible. You don't need to pay anyone to find your Child Trust Fund for you, locate yours today by searching 'find your Child Trust Fund' on GOV.UK.", reports the Mirror.

If you're aware of your Child Trust Fund provider's name, you can get in touch with them directly for more information about your account. However, if you've lost track of your account, HMRC can assist you in locating it by filling out a form on GOV.UK.

This service is available to parents or guardians of children under 18, as well as individuals aged 16 or over who are searching for their own accounts.

To complete the online form, you'll need your National Insurance number and a Government Gateway account, which is free to create. Once you've provided the correct information, HMRC should inform you of your Child Trust Fund provider's name within three weeks.

Alternatively, you can request details by post by writing to: Charities, Savings and International 1, HMRC, BX9 1AU. Try to include as much information as possible, such as the full name, date of birth, address of the account holder, and their National Insurance number.