Any Australian adult (over the age of 18) is able to write a Will, as long as they have testamentary capacity and physical capacity, and have written their Will free of Undue Influence and Duress. These are explained below.

Testamentary Capacity

Testamentary capacity is a legal test to determine whether you are of sound mind, memory and understanding - essentially whether you understand the implications of making a Will. In practice, this means that you:

  • Know what a Will is and its significance,
  • Understand the nature of property that makes up your estate,
  • Can consider the ‘moral claims' upon your estate when choosing who your beneficiaries will be, and
  • Understand and agree with the terms included in your Will.

If you are unsure whether you have testamentary capacity, Safewill recommends seeing a qualified legal professional.

Physical Capacity

A Will is only valid after it has been signed correctly. This requires the testator to have the physical capacity to sign it in a legal sense.

Legally speaking, physical capacity means that you are not blind, are capable of reading, understanding and writing English, and do not have a disability that prevents you from signing the Will.

Undue Influence  

Undue influence refers to a situation where you have been put under such pressure or influence that you are no longer writing their Will ‘freely'. It can occur both where there is an intention to influence someone, or a situation where the person applying the influence does not mean to do so, but it has that effect.

Where undue influence has occurred, a Will is not deemed to be legally valid.


Similar to undue influence, duress is when threats of physical violence, harassment, damage to property or the refusal to complete some action result you being forced to write your Will in a particular way. Again, in such a situation your Will is not legally valid.

If you are unsure of how these requirements apply to your unique situation, we recommend that you seek independent advice.

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