Who will you leave your money to? Your ex-spouse? The taxman? Prince Charles? Unless you draw up a will, any one of them could be a possibility.
Meanwhile, your long-term partner, stepchildren or fiance could miss out.
October is 'Free wills month', when participating solicitors will draw up or update a simple will without charge.
Over half (54%) of Britons have not made a will, according to research by Which?
These are just a few of the things that could happen to your money if you don't leave a will, according to financial advisers Hargreaves Lansdown.
If you don't leave a will ...
Your spouse (or civil partner) could be worse off
While jointly-held property and accounts will automatically pass to your spouse, the rest of your estate won't necessarily.
In England and Wales, your spouse will get the first £250,000, and half of the rest, but if you have children, the remainder will be split between them.
If you're holding money you both intended to use, this could cause serious problems.
It could be even worse in Scotland
In Scotland, aside from jointly held property – which passes to them directly – your spouse will get £473,000 worth of residential property, plus furniture and household items worth £29,000.
If you have children, your spouse will get the first £50,000 of any savings and investments and a third of the rest – and the remainder is shared equally between children.
If you don't have children, your spouse will get the first £89,000 and half of what's left – the remainder will be split between your parents and siblings.
It could trigger a needless tax bill
If you have a sizeable estate, the rules could mean leaving more than £325,000 to your children or other family members – excluding your home – and triggering a tax bill.
If you leave everything to your spouse, it will pass tax-free.
Your long-term partner could receive none of your savings or even their home
If you're not married or civil partners, it doesn't matter if you've been together for 30 years, and it doesn't matter if you're engaged – aside from any jointly owned property or accounts, your estate will go to your children.
If your children have passed away, it will go to grandchildren and then great-grandchildren.
If you have no children, it will pass to other family members in a specific order: parents, brothers or sisters, half brothers or sisters, grandparents, then uncles or aunts.
If you own a property as tenants in common instead of joint tenants, your half of the property will go to other members of the family.
And if you have no close family members, there's a risk it could end up belonging to a long lost aunt – who wants to sell.
Separation doesn't change the rules
Unless you're divorced, you're still treated as a spouse, so you could have been separated for decades and living with a new partner, and your estranged spouse will inherit.
Stepchildren get nothing
Even if you brought up a stepchild as your own, unless you adopted them, they'll receive nothing.
If your biological children have been adopted, they get nothing
If you have biological children but they have been adopted into another family, they don't qualify as your children from an inheritance perspective.
Grandchildren get nothing unless their parents have died
In some families this isn't an issue, but where parents and children don't have straightforward relationships, or where children have problems with money, it could mean grandchildren miss out.
You won't get to decide who gets heirlooms and items of sentimental value
Unless these are classed as investment, they'll be considered chattels and left to your spouse.
If you always promised a particular child, family member or friend they'd receive something specific on your death, you can't be certain that will happen.
If you don't have any family, it could go to Prince Charles
In most of the UK, it will go to the crown. However, if you live in Cornwall, it will specifically go to Prince Charles, who gives it to charity.
If you live in the Duchy of Lancaster, it will go to the Duke of Lancaster – the Queen – who gives some to charity and uses some to maintain the estate.
A surviving unmarried partner can apply to the crown for a grant from the estate – but they can refuse.
Deed of variation
If someone dies without a will, and you know how they would have wanted their estate divided up, you can draw up a deed of variation within two years of their death, and change the way the estate is left.
However, you will need the agreement of everyone who would have benefited under intestacy laws, and to complete the legal process.
If children under the age of 18 would have benefited under intestacy rules, they cannot agree to a deed of variation, so it would need to go through the courts – which becomes much more expensive.
Wedding of Charles and Diana
Wedding of Charles and Diana
Lady Diana Spencer with her father Earl Spencer on their way to St. Pauls Cathedral in the City of London, for her marriage to The Prince of Wales.
Exactly a month before the Royal wedding and Fred English, 85, patriotic from hat to shows, has his Manor Road house in East Molesey, Surrey, decorated for the Royal wedding.
THE OFFICIAL ROYAL WEDDING CAKE FOR DIANA SPENCER AND PRINCE CHARLES MADE BY THE ROYAL NAVY'S COOKERY SCHOOL 5FT HIGH AND 255 ILBS HMS PEMBROKE IN CHATHAM
A London Routemaster bus painted with ribbons and bows to look like a giant wedding present.
James Cleverley, 7, and Leisa Winstanley, 11, with their winning plate designs made up to become rare Royal Wedding Presents and presented to them in London. The plates were hand painted and made into a limited edition - one for each of the children and one of each for Prince Charles and Lady Diana. James of Horningstoft, Norfolk and Leisa, from Truro, Cornwall, entered their designs in the Blue Peter Royal Wedding Plate competition on the BBC.
A message from the City of London Corporation pasted onto the railway bridge at the bottom of Ludgate Hill, London, and destined to be read by the Prince of Wales and Lady Diana Spencer when they are en route to their wedding at St. Paul's Cathedral.
A firework display in Hyde Park, London, to celebrate the marriage of Prince Charles and Lady Diana Spencer.
Grandmother Kathleen Lucus knits to pass away the hours outside Buckingham Palace, London, one of many who have made all night vigils waiting for the Royal wedding of Lady Diana Spencer to Prince Charles.
Scenes outside St Paul's Cathedral in London as young and old awaken from a night in sleeping bags to secure vantage points for seeing the royal wedding.
Brian Balmer, a 19 year old Student from Hindsford, Atherton near manchester, stakes his claim to a seat outside at St. Paul's Cathedral to watch the wedding.
Nancy Reagan at Fitzroy Square in London. She will represent her husband, US President Ronald Reagan, at the wedding of Prince Charles and Princess Diana.
Balloons join the escort of the Blues & Royals for Prince Charles and the Princess of Wales as they drive in an open landau to Waterloo Station from Buckingham Palace. Behind is Lt Col Andrew Parker-Bowles
Earl Spencer (right) accompanies his daughter Lady Diana Spencer at her wedding to the Prince of Wales at St Paul's Cathedral, London.
A FINAL WAVE TO THE CROWDS FROM THE PRINCE OF WALES ACCOMPANIED BY PRINCE ANDREW (RIGHT) BEFORE ENTERING ST. PAUL'S CATHEDRAL, LONDON
Earl Spencer (right), accompanies his daughter Lady Diana at her wedding to the Prince of Wales, at St Paul's Cathedral, in London. * 25/1/96 A Church of Scotland clergyman claimed that the Earl confessed to him in 1947 that he had a romance with the young Princess Elizabeth before she became Queen.
Earl Spencer leads his daughter, Lady Diana Spencer, down the aisle in St Paul's Cathedral, for her wedding to the Prince of Wales. * 29/7/81 of Earl Spencer leading his daughter Lady Diana Spencer down the aisle of St Paul's Cathedral, London, for her wedding to the Prince of Wales.
On the balcony, Buckingham Palace, the Princess of Wales laughs as she places her hand on the shoulder of Edward Van Cutsem, one of the Page boys at her wedding to the Prince of Wales. Also visible are Clementine Hambro (a bridesmaid) and Nicholas Windsor (Page Boy).
The newly married Prince and Princess of Wales (formerly Lady Diana Spencer) kiss on the balcony of Buckingham Palace after their wedding ceremony at St. Paul's cathedral.
The Prince of Wales and his bride Lady Diana Spencer during their wedding ceremony at St Paul's Cathedral.
The Prince and Princess of Wales leave St. Paul's Cathedral in a carriage after their wedding on 29 July 1981.
The official group photo at the wedding of the Prince and Princess of Wales.
The Queen Mother and Prince Andrew, driving back from St Paul's in an open carriage after the wedding of Prince Charles to Lady Diana Spencer.
The Princess of Wales in her bridal gown at Buckingham Palace after her marriage to Prince Charles at St. Paul's Cathedral.
Prince Charles, Prince of Wales and Diana, Princess of Wales leave St. Pauls Cathedral in London following their wedding on July 29, 1981.
Diana, Princess of Wales is led down the aisle of St. Paul's Cathedral by her proud father, Earl Spencer, on her wedding to Prince Charles, Prince of Wales on 29 July 1981.
Diana, Princess of Wales enters St. Paul's Cathedral on the hand of her father, Earl Spencer, for her marriage to Prince Charles, Prince of Wales on 29 July 1981.
Queen Elizabeth II and the Duke of Edinburgh make their way to St Paul's Cathedral for the wedding of the Prince of Wales and Lady Diana Spencer.
**FILE PHOTO** Diana, Princess of Wales, wearing an Emanuel wedding dress, and Prince Charles, Prince of Wales leave St. Paul's Cathedral following their wedding on 29 July 1981.
Designers Elizabeth and David Emanuel are holding an auction of dresses worn by the late Princess Diana. The dresses are to go up for auction on June 8, 2010 in London, at specialist vintage fashion auctioneers Kerry Taylor Auctions.
The Prince of Wales and Prince Andrew make their way to St Paul's Cathedral
The Duchess of Kent and her daughter Lady Helen Windsor on route to St Paul's Cathedral for the wedding of the Prince of Wales and Lady Diana Spencer
The newly married Prince and Princess of Wales leaving St Paul's Cathedral past the Press Association Building on Fleet Street, on their way back to Buckingham Palace.
The Prince and Princess of Wales walking down the aisle after the wedding service at St Paul's Cathedral.
The Prince and Princess of Wales on the balcony at Buckingham Palace after their wedding
The Prince of Wales, and his supporters, Prince Andrew and Prince Edward, arrive at St Paul's Cathedral for his wedding to Lady Diana Spencer.