Some 58 per cent of UK adults do not have a will in place.
Research by unbiased.co.uk was conducted to coincide with the start of Write a Will Week, which gets underway today (October 22nd).
Those individuals who have failed to safeguard the financial future of their loved ones have no guarantee that their assets will be passed on as they wish.
One-in-ten Britons wrongly think their estate will automatically go to the right people, while 42 per cent have so far failed to consider the impact of inheritance tax if they do not draw up the document.
Across the UK, those in the south-east (49 per cent) are most likely to have a will.
Karen Barrett, Chief Executive of unbiased.co.uk, said: "Too many people are simply unaware of the control that having a will gives you and its importance in ensuring your loved ones receive what you intended them to."
She added individuals should consult a solicitor or financial adviser if in doubt, as they will be able to help them make sense of current inheritance rules.