Mistakes That Can Void a Will—And How Lawyers Prevent Them

Not all wills are watertight. In fact, plenty get challenged, and some are thrown out altogether. It’s not always because of major drama either. 

Sometimes, it’s down to simple mistakes that could have been avoided with the right guidance. If you’re writing a will or reviewing one, here’s what to watch out for. 

What Mistakes Can Invalidate a Will?

These are the most common slip-ups that can lead to serious legal problems down the track and how good lawyers help avoid them entirely.

1. Not Following the Formalities

There are strict rules around how a will must be signed and witnessed. Get this part wrong, and the whole thing can be declared invalid. Here’s what can go wrong:

• Missing signatures – If the will-maker (the ‘testator’) forgets to sign, or signs in the wrong place, it might not count.
• No witnesses – A valid will needs two witnesses present at the same time, watching the person sign.
• Unqualified witnesses – Beneficiaries, or the partner of a beneficiary, should not act as witnesses. If they do, they risk losing their inheritance.

How lawyers prevent it

An experienced will lawyer Canberra will oversee the process in person. A lawyer will make sure every signature is placed correctly, that the right people are witnessing, and that it’s all done in one sitting, in line with legal requirements.

2. Using Ambiguous Language

When a will isn’t clear, people interpret it in all sorts of ways. And that leads to conflict.

Here’s an example:

“I leave everything to my children.”

Seems fine, right? But what if the person has biological children and stepchildren? What if one child has passed away—do their kids (the grandkids) now get that share?

A vague sentence can cause huge family issues. The law doesn’t guess what you meant. It only considers what’s written.

How lawyers prevent it

They write everything with precision. That means clear definitions, no vague wording, and legally sound phrasing that doesn’t leave things open to interpretation.

3. Forgetting to Revoke Old Wills

If someone makes a new will but forgets to officially revoke the previous one, things get messy. Multiple wills floating around = a fight waiting to happen.

This can lead to parts of older wills being revived or interpreted as still valid, especially if the new one isn’t clear that it replaces all previous versions.

How lawyers prevent it

They always include a revocation clause that formally cancels any earlier wills. They also ask about previous wills, ensuring nothing contradicts the new one.

4. Leaving Out People Who Could Make a Claim

You don’t have to leave money to everyone, but you do need to consider certain people, or they may challenge your will after you’re gone.

In most states, there are laws that protect “eligible persons”—usually including:

• Spouse or de facto partner (current or former)
• Children (including adult children)
• Stepchildren or anyone financially dependent on you
• People you lived with in a close relationship

If one of these people is left out, and no explanation is given, they may be entitled to a share of the estate through a family provision claim.

How lawyers prevent it

They ask the right questions. A lawyer will go through who’s in your life and who may be eligible, even if you don’t want to include them. If you choose to leave someone out, they’ll help you include a clear statement explaining why.

5. Appointing the Wrong Executor

The executor is the person in charge of carrying out your wishes. It’s a big role, and it comes with legal responsibilities.

Choosing someone unsuitable, like a person who’s disorganised, struggling with their own finances, or likely to cause tension, can lead to major delays and legal action. In some cases, executors can be removed by the court for mismanaging the estate.

How lawyers prevent it

They help you think it through. A lawyer won’t just let you name someone on a whim—they’ll guide you on who’s most appropriate, how to appoint backups, and when it’s better to choose an independent party.

6. DIY Will Templates That Don’t Meet Legal Standards

Online will kits might seem like a shortcut, but they often miss critical details, especially when someone’s circumstances aren’t straightforward.

Here’s what can go wrong:

• The template doesn’t comply with local laws
• Important clauses are missing or too vague
• It doesn’t account for superannuation or jointly owned assets

People often assume that because it’s in writing and signed, it’ll hold up. But that’s not always the case.

How lawyers prevent it

They create wills from scratch, tailored to your situation. No guesswork, no generic wording. They also advise you on what the will can’t cover—like super or assets in trusts—so you don’t accidentally think you’ve sorted everything when you haven’t.

7. Not Updating the Will After Major Life Events

A will isn’t something you write once and forget about. If your life changes and you don’t update it, the will can become outdated or even invalid.

Common life changes that affect a will:

• Marriage or divorce
• Birth of children or grandchildren
• Death of a beneficiary or executor
• Buying or selling property
• Major changes to your financial situation

In some states, marriage automatically revokes a will unless it was made “in contemplation of marriage.” That catches a lot of people out.

How lawyers prevent it

They recommend regular reviews. A good lawyer will flag when you need to make changes and ensure your will reflects your current wishes and relationships.

8. Poor Storage and Lost Wills

Even the best-written will is useless if no one can find it. If the original signed copy goes missing, and only a digital or photocopied version exists, there’s a chance the court won’t accept it. Some people hide their wills so well that nobody knows they exist.

How lawyers prevent it

They store the original in a secure legal archive and provide certified copies to the right people. They also try to ensure that your executor is aware of where exactly the will has been kept. Additionally, they also know ion what ways they can access it when the right time comes!

The Bottom Line? Wills Are Legal Documents—They Need Legal Eyes

It’s easy to underestimate how much can go wrong with a will. Even small slip-ups can cause massive headaches later on. That’s why lawyers aren’t just there to “write the will”—they’re there to make sure it stands up in court, reflects your true wishes, and protects the people you care about.

They know the traps. They ask the right questions. They know what’s enforceable and what’s not.

If your will matters to you—and let’s be honest, it should—then it’s worth doing it properly. Because the one thing worse than having no will at all… is having one that falls apart when it’s needed most.

I hope you found this blog helpful if you wanted to know What Mistakes Can Invalidate a Will. In case there are any other questions, please feel free to let us know by commenting below!