Common Mistakes People Make with Their Will: 5 Lessons Learned

After enough years around estate planning — reading other people’s finished wills, watching families deal with the aftermath of poorly written ones — certain mistakes stop feeling like exceptions and start feeling like a pattern. The same five things come up again and again, in different families, different estates, different countries even. Here are the lessons, as plainly as I can put them.

Lesson 1: The Mistake Isn’t Usually in the Writing — It’s in the Not Updating

If I had to name the single most common mistake with a will, it wouldn’t be a clause or a typo. It would be this: people write a perfectly good will once, and then never touch it again. Marriage, divorce, new children, a change in assets — these are all supposed to trigger a review, and most people simply don’t circle back. A will written at 30 doesn’t necessarily reflect what someone wants at 50, and the document has no way of knowing that unless someone actively updates it.

Lesson 2: Vague Generosity Causes More Damage Than Clear Specifics

I’ve seen “split everything equally among my children” cause more family arguments than almost any other single phrase. It sounds fair. It isn’t specific. One child wants the house, another wants it sold, a third thinks the antique clock should count against someone’s share — and there’s no instruction to settle any of it. The lesson here took me a while to fully appreciate: specificity isn’t cold or transactional, it’s actually the kinder choice, because it removes the argument entirely rather than leaving it for grieving people to sort out themselves.

Lesson 3: People Assume Family Will “Just Work It Out”

This is close cousin to the mistake above, but it’s really about trust rather than wording. Parents assume siblings who got along fine while everyone was alive will continue getting along once money, grief, and old resentments are all in the room together. Sometimes that’s true. Often, it isn’t — and the people who assumed it would be true aren’t around anymore to referee when it goes wrong.

Lesson 4: The Most Common Inheritance Mistake Is Skipping the “What If” Questions

What happens if a beneficiary dies before the will-maker? What if two people named as beneficiaries die at the same time? What if a child is born after the will is written? These aren’t edge cases dreamed up by overly cautious lawyers — they’re exactly the situations that turn a straightforward estate into a legal dispute. The lesson: a will isn’t just a list of who gets what under normal circumstances. It’s supposed to hold up under the circumstances nobody expected either.

Lesson 5: People Get So Focused on “Who Gets What” That They Forget “Who’s In Charge”

Beneficiaries get all the attention. Executors get almost none. But naming the wrong executor — someone disorganised, someone who won’t get along with the beneficiaries, or simply someone who never agreed to the role in the first place — can unravel an otherwise perfectly clear will. This is the mistake that tends to surface only after death, when it’s far too late to change course.

What Are Common Mistakes That People Make? A Quick Recap

Pulling the five lessons together into a simple list:

1. Writing a will once and never revisiting it
2. Using vague, general language instead of specific instructions
3. Trusting family to sort out ambiguity on their own
4. Skipping contingency planning for unexpected scenarios
5. Under-thinking the choice of executor

What Voids a Will in Australia?

Australia is worth its own section here, because the rules differ meaningfully from the UK, and they vary again by state and territory. Broadly, a will can be voided or invalidated by:

• Improper execution. Like the UK, Australian wills must be in writing, signed by the will-maker, and witnessed by two independent adults present at the same time, who aren’t beneficiaries (or their spouses).
• Lack of testamentary capacity, assessed against the same long-standing Banks v Goodfellow test used in the UK — the will-maker must understand the nature of the document, their property, and who might reasonably expect to benefit.
• Marriage. In most Australian states and territories, marriage automatically revokes an earlier will, unless the will was made in contemplation of that specific marriage — similar in spirit to the UK rule, though the exact wording requirements differ by jurisdiction. In the ACT, South Australia, and Western Australia, marriage voids a will entirely; other states apply similar principles with some variation.
• Divorce. A divorce order (not simple separation) generally revokes provisions relating to the ex-spouse, while the rest of the will remains valid — the ex-spouse is essentially treated as having predeceased the will-maker for the purposes of the document.
• Undue influence or lack of knowledge and approval. If the will-maker didn’t genuinely understand or agree with the contents — particularly relevant if the will was prepared by someone who stood to benefit significantly — it can be challenged.
• Multiple or unclear versions. Only the most recent valid will applies; disputes over which version is genuinely the last one are a recurring source of legal conflict.

One important nuance: unlike some parts of the UK, a beneficiary acting as a witness doesn’t void their gift in every Australian state — Victoria and South Australia are exceptions to that rule, while most others (including NSW and Queensland) follow the same principle as England and Wales, voiding the gift rather than the whole will.

Common Mistakes to Avoid

• Treating your will as a one-time task. Life changes; the document needs to change with it.
• Being vague where specificity actually matters. General language invites disputes, not harmony.
• Assuming family dynamics will hold up after you’re gone. Grief changes people; don’t leave it to chance.
• Skipping “what if” scenarios. A will should account for the unexpected, not just the expected.
• Undervaluing the executor decision. The right person matters as much as the right instructions.
• Assuming the same rules apply everywhere. Marriage, divorce, and witnessing rules genuinely differ between the UK, Australia, and even between Australian states.

Final Thoughts

None of these lessons came from anything dramatic — just the same quiet patterns repeating across enough families and enough estates that they stopped looking like coincidence. The good news is that every single one of them is entirely avoidable, and none require anything more complicated than a bit more specificity and a habit of checking back in every few years.

FAQ

What is a common mistake with a will?
Writing it once and never updating it after major life events like marriage, divorce, or having children, leaving outdated instructions legally in force.

What voids a will in Australia?
Improper signing or witnessing, lack of testamentary capacity, undue influence, and in most states, a later marriage (unless made in contemplation of it) — with specific rules varying by state and territory.

What is the most common inheritance mistake?
Skipping contingency planning — not accounting for what happens if a beneficiary dies before the will-maker or if circumstances change unexpectedly.

What are common mistakes that people make?
Vague language, assuming family will resolve disputes amicably, under-thinking the choice of executor, and treating the will as a finished task rather than a living document.