This year marks the first anniversary of child trust fund (CTF) vouchers being sent to parents whose kids qualify for the government saving scheme.
Halifax Financial Services says take-up has been "slow", with a million vouchers not yet invested in accounts.
Even though children in lower income families qualify for an investment of £500, three-quarters of their parents have not yet invested their vouchers.
This is opposed to 70 per cent of parents who are better off, who have already invested their children's savings vouchers - worth £250 each.
CTF vouchers sent a year ago are now nearing their expiry date, Halifax warns.
Unless parents invest these in an account of their choice before the deadline, Inland Revenue will do so on their behalf.
Vouchers not yet invested by parents will be saved in a generic stakeholder account within six weeks of their expiry.
Parents will then be notified of the account details and who the savings provider is, Halifax points out.
Following the merger of Halifax and Bank of Scotland in 2001, HBOS has 22 million customers.
With assets of over £440 billion, it is the UK's largest mortgage and savings provider as well as being a major player in the provision of new current accounts and credit cards in the UK.
With around three million private shareholders, HBOS has the largest private shareholder register in the UK.




