(MONEY Magazine) – What could be more natural than for a husband and wife to own their home and other assets jointly? That way, when one of them dies, the property will automatically pass to the other, 100% free of federal estate taxes. A sensible idea? Not necessarily. ''The potential problems of joint ownership are enormous,'' says Robert Zobel, a tax partner with Deloitte & Touche in Fort Lauderdale. By holding everything in joint name, couples raise the likelihood that the tax collector will end up with a bigger share of their wealth than he deserves. Let's say that stock a couple acquired for $5,000 is worth $50,000 when the husband dies and the wife sells it. Had the husband owned the shares in his name, his widow would owe no tax because the capital gain during his lifetime is not taxable to her. If the couple owned the shares jointly, she would face taxes on $22,500 -- her half of the gain. Worse yet, a couple who own everything jointly risk leaving much less to their heirs than the law permits. Consider this: over their lifetimes, a couple can easily pile up far more than $600,000 -- the maximum that the law lets you pass on tax-free. The Internal Revenue Service takes 37% to 55% over that. But by using other forms of ownership -- and having wills with simple tax-cutting devices called bypass trusts -- you can leave up to $1.2 million | without triggering estate taxes. You and your spouse might consider these common alternatives: -- Sole ownership, which lets you leave an asset to anyone you choose, including your spouse. But the asset must first pass through probate -- the court process of approving a will. -- Tenancy in common, which permits each spouse to own half of an asset. Your spouse will inherit your half only if you say so in your will. Here too, the asset must be probated. These forms of ownership can be used even if you live in one of the nine community property states -- Arizona, California, Idaho, Louisiana, Nevada, New Mexico, Texas, Washington and Wisconsin -- where assets acquired during marriage are usually owned jointly. Switching out of joint ownership can be easy -- with a mutual fund account, for example, you and your spouse need only sign a form. But ownership laws differ in every state, so be sure to consult an estate lawyer first.