Seven Will-Writing Mistakes That Trigger UK Inheritance Disputes (and How to Avoid Them)

In England and Wales, a will is not valid merely because it is written down and signed. Under Section 9 of the Wills Act 1837, the testator must sign the will (or acknowledge their signature) in the physical presence of two or more witnesses present at the same time, and each witness must then sign in the presence of the testator.

If one witness steps out of the room while the testator signs, or signs the document later at home, the entire will is invalid and the estate falls back into an earlier valid will or into intestacy. It is also important to note that the temporary pandemic concession allowing remote video witnessing of wills in England and Wales ended for wills made after 31 January 2024.

Section 15 of the Wills Act 1837 contains a strict anti-fraud rule: if a person who witnesses a will is also named as a beneficiary — or is married to, or in a civil partnership with, a named beneficiary at the time of witnessing — the will itself remains valid, but the gift to that beneficiary is utterly null and void.

This mistake happens frequently when homemade wills are signed at a kitchen table and an adult child's partner or spouse is asked to act as the second witness. Choosing two completely independent adult witnesses who have no financial interest in the estate avoids this trap entirely.

Under Section 18 of the Wills Act 1837, entering into a marriage or civil partnership in England and Wales automatically revokes any previous will, unless the will explicitly states that it was made in contemplation of that specific marriage or civil partnership to that named person.

Although the Law Commission's May 2025 report ('Modernising Wills Law') recommended abolishing automatic revocation by marriage to help combat predatory marriages, that recommendation remains part of a draft bill awaiting Parliamentary enactment; under current law in force today, marriage still revokes an existing will.

Conversely, separation does not alter a will. Until a final divorce order (decree absolute) or civil partnership dissolution order is granted, an estranged spouse remains entitled to inherit whatever the will leaves them — or to claim their statutory legacy under intestacy. Even after a final divorce order (which treats the former spouse as having died on the date of the order under Section 18A), reviewing and replacing the will is essential to ensure substitute executors and residuary gifts still make sense.

Couples often make straightforward mirror wills leaving everything to each other on the first death, and then to the children on the second death. However, an outright mirror will is not a binding contract: after the first partner dies, the surviving partner owns the inherited estate outright and is legally free to make a new will.

If the surviving partner later remarries, their existing mirror will is automatically revoked by the new marriage unless re-drafted in contemplation of it; and even if they make a new will, they may leave the combined estate to a new spouse or step-family. Where couples have children from previous relationships, they often explore whether holding the family home as tenants in common alongside a life-interest will trust is more appropriate than an outright gift.

A will can only dispose of property interests that belong to the deceased's estate. If a couple owns a property as beneficial 'joint tenants', the deceased's share passes automatically by survivorship to the surviving co-owner on the moment of death, overriding anything written in the will.

Where a testator intends their distinct percentage share of a property to pass to children or into a will trust, the joint tenancy must be severed so the owners hold the equitable interest as 'tenants in common'.

Vague phrases such as 'divide my belongings fairly' or naming specific bank accounts that are closed and moved years later (which can cause a specific gift to fail by ademption) frequently lead to disputes between executors and beneficiaries. Every major gift should also name a clear substitute beneficiary in case the primary beneficiary dies before the testator.

Equally, crossing out words or writing notes on an already-signed will without re-signing and re-witnessing in full compliance with Section 21 of the Wills Act 1837 is ineffective and can trigger Probate Registry requisitions demanding affidavit evidence of the document's condition.

For business owners and limited-company directors, leaving private company shares in a will without checking the company's articles of association or shareholders' agreement can create an immediate deadlock if the articles contain pre-emption rights restricting share transfers on death.