The two of you are living together and engaged to be married. You've entered into the, "What's mine is yours and what's yours is mine" frame of mind. You borrow his bike, his clothes; he plays your CDs and uses your laptop. Sometimes, you leave your engagement ring at home, afraid of losing or damaging or, perish the thought, giving someone the chance to steal it. But you aren't sure if it's covered by your betrothed's home contents insurance. You've only been living together a few months in what used to be exclusively his apartment. Is any of your stuff insured under his policy?

Now is the time for the two of you to create an actual home inventory, not a guesstimate, of all the personal property in the apartment you'd like to insure against damage or loss. Even though you aren't married yet, some states and insurers will allow you to obtain apartment renters' insurance together—one policy, both of your names—while others will make each of you get your own policy.

"Most renters are underinsured by 50 percent," says Steve, a veteran property and casualty agent for State Farm in Austin, Texas, who asked that his last name be withheld. "They don't adequately know the replacement value [of their property]." Steve also feels that it's in a domestic partner's best interest to have a separate policy until the marriage is official. "That's where the problems start," he said, referring to the possibility of a joint check from the insurance company for property that belonged to only one partner.

To create a home inventory, which will help you decide how much home contents insurance you need and make filing a claim easier, add up the cost of everything you would want to replace if it were damaged or stolen. Record model numbers, dates and places of purchase. Take photographs or make a video of these items and place a copy of the inventory in a safe place away from your home.

Bear in mind that most renters' insurance policies have standard coverage limits, i.e., a $2,000 total limit on jewelry that is stolen. Be sure to review these limits and, for expensive jewelry and other valuables you may want to consider buying a "floater." These additions to your policy provide higher limits and broader coverage. "They're for things that were not thought of before the basic policy was written," explains Steve.

As for home owners, it isn't difficult for unmarried couples to buy homeowner's insurance together at the same rates offered to the married, as long as both partners own the house. If the title to the property bears only one name, the personal property of the other will not be automatically covered by the policy. The non-owner can perhaps be added as an occupant—check with your insurer about this—or may need to get separate renter's insurance.

Finally, if you or your mate work out of your home, you may need a special policy to cover expensive equipment, not to mention extra liability coverage if you receive clients in your home. Just one more thing to think about as you merge households and begin to acquire property of real as well as symbolic value.