If you have a child:

The Family Home Protection Act prevents one spouse from selling the family home without the consent of the other spouse, even if the home is held solely in his or her name. But this Act does not help out cohabiting couples, even if they have a child together. "You might think that the Family Home Protection Act would apply, but it doesn't," says Ms Kerri O'Connell. If there is no will or side agreement and the couple are tenants-in-common, the share will pass back to the estate of the deceased partner.

Cohabitees with a child could will their share of a property to the child and face a much lower inheritance tax bill than if they left it to their partner. But this would mean the property would be tied up in a trust.

"If the relationship broke down, either could sell and put the other out on the street because they own their own shares absolutely. The only legal obligation is maintenance to the child," she says.

A church annulment and remarriage will not save on tax:

In order to be exempt from capital acquisitions tax, a couple has to be married according to civil law, notes Mr Richard Grogan of O Flynn Exham & Partners.

A church annulment followed by remarriage is not enough. The partner or partners in question must obtain a formal divorce. If they don't, the State recognises the couple as cohabitees rather than spouses and they will face a large inheritance tax bill if one partner dies.

Be careful when making mortgage repayments:

If one cohabitee earns significantly more than the other, they may pay more than half the mortgage repayments. But if the relationship breaks down, they have no automatic entitlement to anything more than a half-share of the property.

"Tenants-in-common have to be very careful on that issue," says Mr Donal Ryan, a financial adviser at Coyle Hamilton. Evidence is needed that one person clearly paid more than the other.

If the property is in one name only, it is important that the other partner does not make any repayments. "If it's all in his name, she has no claim whatsoever if she has made repayments and they split up," says Ms O'Connell.

Don't add to the property's value:

The same court battles would take place if a partner who did not own the property he or she lived in was DIY-friendly and made renovations that had increased the market value of the property - perhaps by building an extension or landscaping the garden.

"The increase in the value of the property might be 10 or 20 per cent, but they could lose it all in legal fees trying to make their claim," says Mr Ryan.