A badly drawn-up will can lead to family disputes and years of expensive legal wrangling, says Julian Knight, author of a recently published guide to wills and inheritance tax. 

Five common problem wills

Question: What's worse than dying without a will?

Answer: Dying with a problem will. Problems come in all shapes and sizes. A badly drawn-up will can lead to family disputes and years of expensive legal wrangling. Under certain circumstances a problem will can be deemed invalid and not worth the paper it's written on!

At the very least, a problem will can hold up the probate process, creating a headache for your executors. Here's a quick look at some problem wills - take heed and make sure that yours is up to scratch.

An unsigned will

A will is a legal document and must be signed by the testator (the official name for the person making the will). Everyone may know that the will is yours; you may have discussed its contents with your nearest and dearest and you may even have written it in your own hand. Nevertheless, your will has all the legal weight of a shopping list until you sign it. You can put your signature anywhere on the will document at the start, middle or end. However, it's best to sign the will at the end to keep things simple.

Don't forget to put the date on the will when you sign it. Your executors can more easily decide whether it is likely that you have made a new will since.

An unwitnessed will

Signing your will isn't enough: you must also have your signature witnessed. You need two witnesses and they must be present when you sign your will. Your witnesses must be over 18 and be of sound mind. If your will is not witnessed it is deemed invalid and any previous (witnessed) will replaces it. If you didn't make a prior will, you are deemed to have died intestate (without making a will at all). Don't have a beneficiary or the spouse of a beneficiary witness your will. Beneficiaries who witness a will are automatically disinherited.

Getting married = new will

Your old will is automatically revoked when you get married (unless you live in Scotland). Your will document with all those smart tax-saving plans and painstaking allocation of gifts might as well never have existed.

What do you do? Draw up a new will as soon as possible after marriage. You can make a will in expectation of marriage, which names your betrothed. This type of will won't be revoked by marriage.

Getting divorced = new will

If you get divorced your former spouse is automatically cut out of your will. The rest of the will still takes effect. This situation can create a real headache because the spouse is usually the main beneficiary. If your ex-spouse is cut out, then what money was supposed to go to them ends up in the estate residue.

The estate residue is what's left in your estate after creditors and beneficiaries have been paid. In cases where the spouse is disinherited by divorce, the estate residue can be worth a lot of money and unless you've distributed that money in your will it will be distributed under intestacy. Divorce should nearly always prompt you to make a new will.

A will leaving dependants out in the cold

Laws are in place to stop you cutting your spouse or dependants out of your will so you will have to squash that mean streak. Under the Inheritance (Provision for Family and Dependants) Act 1975, your spouse and those people deemed dependant on you at your death can ask the court for money from your estate.

In reality, not all dependants are equal in the eyes of the court. The key is to make sure your spouse and children are looked after. The court will understand if there isn't enough to go around all your dependants just as long as you do your best by your spouse and children.