Challenging a will 

It’s good to have a will, to ensure that the people and organisations you care about are provided for after you die. It’s important that your will is properly signed and witnessed, and kept up-to-date.
Keeping your will up-to-date and trying to be fair in how your estate is to be divided among the people who survive you, could save them from the stress and cost of someone challenging your will when you’re gone.

If you’re considering challenging a will

If you feel you’ve been short-changed by the will and are thinking of contesting it, be aware that doing so can cost you a lot of time and money. 

You might want to consider an alternative to going to court, which is to seek mediation with the will’s other beneficiaries. With the help of an independent mediator you may all be able to agree on a solution which suits everyone, avoiding the expense of going to court. Your local CAB can help you look for a mediator.  
If mediation is unsuccessful or unwanted and you wish to pursue the matter, you will probably need advice from an appropriately experienced lawyer. (Your local CAB can help you look for a lawyer.)
Ask your lawyer to give you, in writing, their professional opinion on your chances of success if you proceed, as well as an explanation of the process and a breakdown of the likely fees involved.

To challenge a will you will need to go through either the High Court or the Family Court - depending on what grounds you are making the challenge - and you or your lawyer will generally need to file your claim within 12 months of the grant of probate (unless your challenge is on the grounds of validity, in which case you need to file before probate is granted).

Once you notify the court that you intend to challenge a will, the executor or trustee (the person responsible for distribution the deceased’s estate according to the will) must not distribute any of the estate except to pay debts, expenses and funeral costs.

Grounds for challenging a will

A will can be challenged on the following grounds:
On the grounds that it is invalid -
For example, you might be able to prove to the court that the will wasn’t properly witnessed or that the deceased wasn’t of sound mind when they signed the will. If the will is determined to be invalid, either an earlier will can be reinstated, or the estate will be distributed under the rules of intestacy. 

On the grounds that the deceased had a moral duty to provide for you -
For example, if you fell out with one of your parents and were subsequently left out of their will, you could make a case that they had a moral duty to provide for you and that by leaving you out of their will they have breached that duty.

For the will-maker, the Community Law website has some tips for avoiding claims under the Family Protection Act.

On the grounds that as the spouse of the deceased you are entitled to claim a division of relationship property -

This means that if your spouse, civil union partner or de facto partner (of at least three years, or less if you have a child together) dies, you can choose to claim half of the relationship property rather than accept whatever has been bequeathed to you in their will (or, if there is no will, what you would inherit under the rules of intestacy).

On the grounds that the deceased had promised to leave something in return for something you did for them, but had not updated their will accordingly -

For example, if you were the deceased’s much-loved caregiver they may have promised to leave you money or an item they knew you liked. If they had not managed to update their will to accommodate their promise, you could challenge the will to make a claim for the promised share of their estate.