If the two of you decide to buy a house together, in addition to making sure that both of your names are on the deed, you should make sure the deed also indicates your preferred method of jointly holding property. Specify either “joint ownership with rights of survivorship” or “tenants in common.”

Joint Ownership with Rights of Survivorship

The simplest method of transferring property is joint ownership with rights of survivorship, which means that if one of you dies, the other automatically inherits the property. You avoid inheritance tax because the house isn't considered part of the estate. The downside is that you don't have the option of selling your share or leaving it to someone other than your partner, and joint ownership provisions in the deed will override any bequest in your will.

Tenants in Common

Being tenants in common means that each of you owns half of the house. If you die, your share will go to the person or persons indicated in your will (if you have one), or else to your next of kin. This method of ownership allows for owners with unequal equity. For example, you may own 75 percent of the house and your partner may own 25 percent. Each of you can sell or give away your share or leave it to one or more individuals of your choice, such as kids from a previous relationship. Having a will is critical if you own property as tenants in common.

Who Gets the House if You Break Up?

Your nonmarital agreement should spell out what will happen if both of you want to keep the house when you break up. How will you decide who goes and who stays? Does the person who gets the house buy out the person who's leaving? How is the buyout price calculated? Is it half the equity in the house, or is an amount deducted equal to the Realtor fees that would have been paid if the house had been sold? These issues are fodder for heated arguments if you don't spell them out ahead of time.

If one of you contributed more to the purchase of the house than the other, your nonmarital agreement should spell out how this will be compensated if you break up. Even if you each contributed 50 percent, you may want to allow for one person to build equity or offset contributions to the household fund by doing repairs or improvements on the house.