An old will can remain valid long after the life around it has changed. For some Cardiff families, one overlooked instruction could turn a once-sensible plan into an unexpected £50,000 bill.
The mistake can stay hidden for years
The costly error is not always failing to make a will. It can be assuming that a document written five, ten or twenty years ago still reflects the family, assets and intentions it was designed to cover.
A will does not update itself when a home rises in value, children become adults, a second marriage creates a blended family, or an executor is no longer suitable. The document may remain valid while producing an outcome its maker would no longer choose.
That mismatch often stays hidden until the estate must be administered, leaving the family to interpret instructions written for circumstances that no longer exist.
Cardiff estates are being measured against new realities
Office for National Statistics and HM Land Registry figures put Cardiff’s average house price at £273,000 in May 2026. Home-movers paid £334,000 on average. In May 2016, the citywide average was £188,278, so the headline figure has risen by about 45 per cent over ten years.
The inheritance tax nil-rate band remains £325,000, while a residence nil-rate band of up to £175,000 may apply when a qualifying home passes to direct descendants. Both are fixed through the 2030 to 2031 tax year. The £322,000 statutory legacy under intestacy is now slightly below Cardiff’s average home-mover price.
The Wills Act 1837 underpins will validity. The Administration of Estates Act 1925, amended by the Inheritance (Provision for Family and Trustees’ Powers Act 2014, governs distribution where no valid will exists.
Where the £50,000 problem can arise
A clause that no longer fits
Consider a simplified example. A will made years ago leaves a solely owned investment portfolio to adult children on the first death, while the family home passes to a spouse. The portfolio, once modest, is now worth £450,000.
Assume no debts, lifetime transfers or other exemptions or reliefs affect the calculation. The first £325,000 could be covered by the nil-rate band. The remaining £125,000 could face inheritance tax at 40 per cent, producing a £50,000 bill.
The wording may have made sense when the portfolio was smaller. The risk lies in allowing it to operate after the figures have changed. This is an illustration, not advice for a particular estate.
Intestacy follows its own formula
Where a person dies without a valid will and leaves a spouse or civil partner and children, the survivor receives personal chattels, the first £322,000 of the net estate and half of what remains. The children share the other half.
That formula may not match what the deceased expected. An unmarried partner has no automatic entitlement under intestacy, however long the couple lived together.
Budget reforms changed the backdrop
Since 6 April 2026, the combined allowance for 100 per cent Agricultural Relief and Business Relief has been £2.5 million. Qualifying value above it generally receives 50 per cent relief. From 6 April 2027, most unused pension funds and pension death benefits will enter estates for inheritance tax purposes.
Those changes do not make every older will unsuitable. They do make assumptions involving farms, private businesses and substantial pensions worth checking.
Blended families need deliberate choices
Second marriages, stepchildren and children from previous relationships can create competing priorities. Someone may wish to support a surviving partner while protecting an inheritance for children, but a generic or outdated will may not achieve that balance.
Cardiff households reassessing those decisions can approach Maplebrook Wills, a professional will writing service that prepares wills around current family and estate circumstances. Charles Quist, Principal Adviser at Maplebrook Wills, said local will-writing discussions have changed as property values have risen and the reforms announced at Autumn Budget 2024 have begun to take effect.
Charles Quist on what Cardiff families are overlooking
Quist said: “Over the past two years, more Cardiff families have started reviewing wills that still look valid but no longer match the life around them. Higher property values, blended family arrangements and the pension change due in April 2027 are prompting people to reconsider what they own and who they want to benefit. The recurring concern is not always poor drafting, but drafting created for circumstances that have since changed. Considered will planning matters more than it did five years ago because today’s assets, relationships and intentions need to be recorded clearly.”
His comments are a general sector observation and do not amount to legal, tax or financial advice.
Four checks worth making now
Read the will with fresh eyes
GOV.UK recommends reviewing a will every five years and after major life changes. Marriage normally cancels an earlier will, while separation, divorce, having children, moving home or the death of an executor can affect whether it still works as intended.
Rebuild the estate snapshot
Use current values for property, savings, ISAs, investments, relevant life policies, business interests and pensions. Old statements and a home’s original purchase price do not show the estate as it stands today.
Look again at the family structure
Consider marriage, civil partnership, cohabitation, divorce, stepchildren, grandchildren, vulnerable beneficiaries and dependent relatives. A will written before those relationships changed may direct assets in an unexpected way.
Match the drafting to today’s intentions
A review does not automatically mean replacing the will. It means checking whether the executors, guardians, gifts and beneficiaries still match the intended result, and recognising when specialist advice is needed.
Know which professional service is required
Will writing is not a reserved legal activity in England and Wales, although specified probate work is reserved. A professional will writing service can draft a will and explain its scope. Solicitors are regulated for the legal services they provide.
Complex trusts, contested estates, business succession, overseas assets and tax-sensitive arrangements may require a solicitor, tax adviser, financial adviser or another appropriately qualified professional. Families should understand who is responsible for each part of the work.
The warning reaches beyond the capital
Cardiff had the third-highest average house price among Welsh local authorities in May 2026, but the underlying issue is wider.
Families across South Wales also face changing property values, pension arrangements and family structures. Welsh farming and business-owning households have an additional reason to revisit older plans following the April 2026 relief changes.
The figures differ between estates, but the principle does not. A will should reflect the assets, relationships and intentions that exist now.
The expensive assumption is that nothing has changed
The £50,000 mistake is not obscure legal theory or an unusual family arrangement. It is allowing instructions written for a different property value, balance sheet and family to operate without review.
The average Cardiff home has risen materially in value over the past ten years. The UK inheritance tax framework has changed meaningfully, and family circumstances rarely stand still. Wills written against different circumstances can therefore stop reflecting current reality, with a £50,000 cost capable of falling to the next generation of a Cardiff family. Addressing the question this year is one of the more useful household decisions available.
This article is for general information only and does not constitute legal, tax, financial or estate planning advice. UK will writing rules, inheritance tax thresholds, allowances and reliefs are subject to legislation and may change. Individual will writing and estate planning decisions require consideration of specific personal, family, financial and property circumstances that this article cannot address. Anyone considering will writing, estate planning or inheritance tax planning should take advice from qualified professional advisers appropriate to their circumstances. Maplebrook Wills is a professional will writing service, not a firm of solicitors. Will writing in England and Wales is not a reserved legal activity except for specific probate-related work. Complex estate planning matters, contested estate matters and regulated legal work require appropriately qualified legal advice.
