Contesting a Will: Who Can Challenge and On What Grounds

Every family has heard a version of "I'll contest the will". In practice, successful challenges are the exception, the grounds are narrow, and the costs — financial and emotional — are serious. Here is how it genuinely works in England and Wales, whichever side of a dispute you are on.

First: there is no "fairness" ground

English law starts from testamentary freedom — you can leave your estate to whoever you like, including unequally between children, or to none of them. A will is not invalid because it is surprising, hurtful or unfair. Challenges succeed on specific legal grounds, not on disappointment.

The grounds that actually exist

• Invalid execution. The signing and witnessing rules were not followed — wrong number of witnesses, witnesses not present together, a beneficiary witnessing. This is the cleanest ground when the facts support it; our guide to valid wills shows what should have happened.
• Lack of testamentary capacity. The person did not understand what they were doing, what they owned, or who might expect to inherit — typically argued around dementia. Medical records and the will-drafter's notes decide these cases.
• Undue influence. Someone coerced the person into the will. Genuinely hard to prove: courts require evidence of actual coercion, not just opportunity and a suspicious outcome.
• Lack of knowledge and approval. The person did not know or approve the contents — suspicious circumstances, like a major beneficiary preparing the will, shift the burden of proof.
• Forgery or fraud. Rare, handwriting-expert territory.

The separate route: the Inheritance Act claim

Distinct from attacking the will's validity, the Inheritance (Provision for Family and Dependants) Act 1975 lets certain people claim the will (or intestacy) failed to make "reasonable financial provision" for them: spouses and civil partners, former spouses who have not remarried, cohabitants of two-plus years, children — including adult children, though their claims are harder — and anyone financially maintained by the deceased. This is the route for the partner left out or the dependant cut off, and it must usually be issued within six months of the grant of probate. Miss that and you need the court's permission to proceed at all.

What it costs and how it usually ends

Contested probate is expensive — genuinely contested cases that reach trial can consume tens of thousands of pounds per side, and the loser generally pays the winner's costs. The realistic picture: most disputes settle at mediation, precisely because everyone's costs risk is so ugly. If you are considering a challenge, act fast (enter a "caveat" at the probate registry to pause the probate process while you investigate), get a merits opinion from a contentious probate solicitor early, and be honest about whether the estate is big enough to justify the fight.

If you are writing a will you expect to be challenged

Unequal treatment or excluded relatives? Reduce the attack surface: use a solicitor (their file notes become evidence of capacity and intention), consider a doctor's capacity assessment for older testators — the "golden rule" — include a letter explaining your reasoning, and review the will while clearly well. None of this prevents a challenge; all of it makes one likelier to fail, which is often enough to prevent it being brought. See also updating your will safely.

This is general information about the law in England and Wales, not personalised legal advice. Rules, thresholds and processes change, and Scotland and Northern Ireland have different rules in places — for anything that depends on your own circumstances, it is worth speaking to a solicitor (ideally one accredited by STEP or Solicitors for the Elderly) or checking GOV.UK and Citizens Advice for current detail.