Most adults in the UK have not written a will, including three-quarters of people in their thirties.It may come as no surprise that almost nine out of 10 people aged 20-29 have no will in place according to research by the financial adviser comparison site unbiased.co.uk.But perhaps slightly more unexpected is the finding that almost two-thirds of 40-49 year olds and 60 per cent of 50-59 year olds have no will - so if they died now, they would die intestate, which means their their wealth would be dispersed according to state rules.How likely you are to have a will in place depends not only on age but also on where you live. In Brighton for example, 70 per cent of respondents said they have no will. In contrast, only 55 per cent of Glaswegians said they lack a will. PUTTING IT OFFThe most common reason for not having a will is that people are putting it off until they are older - including about one in seven people in their sixties. Meanwhile, 17 per cent say they have too few assets to make a will necessary.'Our research made two especially interesting findings, which are rather at odds with each other,' says Karen Barrett, chief executive of unbiased.co.uk.'We confirmed that people really do want to ensure their loved ones are taken care of after they've gone - but that most aren't doing anything about this.'Writing a will clearly has significant emotional implications, so it's likely that people delay doing it through a mixture of denial and simply not getting around to it.'People should also remember that it's simple, inexpensive, and saves families from a significant amount of extra stress. Now that pension freedom has completely rewritten the rule book on what can and cannot be inherited, making your wishes legally binding has never been more essential.'Even those who already have a will in place could be caught out. In July, the government announced an extra inheritance tax-free allowance of £175,000 (in addition to the existing nil rate band of £325,000 per person) for parents who pass the family home to their children from 2017, taking the total to £1 million by 2020 for couples who own their home.People who neglect to update their wills could risk being wrong-footed by the new rules.