En español  |  Why work hard to build wealth only to have your wishes thwarted or your family left with much less than you anticipated? From wills to trusts and beyond, protect your loved ones by avoiding these four costly but common estate-planning mistakes.

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1. Forgoing an expert's review. There's nothing wrong with saving a few bucks by drafting your own estate-planning documents. You can find templates for basic wills and such online or in bookstores. Just be sure to invest in a review of the final documents by an expert to be sure everything is in order.

"Ninety percent of the online estate-planning documents I see don't do what the people think they're going to do," says Leanna Hamill, an estate planner and elder law attorney in Hingham, Mass. "I've seen people use online documents, documents out of estate-planning books or documents borrowed from friends. But they screw up their estate plan because they don't understand the legal and technical aspects of the documents."

Common mistakes Hamill has seen? One client signed a deed transferring his house to a trust but hadn't properly created the trust. Thus, the deed had no effect. Another client's confusion over the term "beneficiary" resulted in the immediate transfer of all his property to his children and required him to pay them an annual income, leaving his wife in the cold.

Proper estate planning ensures your wishes will be followed. Remember to revise your estate plan when your family or the law changes. — Photo by Masaaki Toyoura/Getty Images

2. Failing to tie your business to your estate plan. If you own a business, include it in your estate plan. "Parents sometimes don't want to talk to their kids about it and just leave the business to the kids," says Steve Ciepiela, president and owner of Charles Stephen & Co., a financial planning firm in Albuquerque, N.M. "That's a huge mistake."

A typical conundrum is how to provide equally for children who work in the family business and those who don't. Ciepiela had hounded a couple with five children to do estate planning that covered their business. But they stuck with simple wills and died within five months of each other. At a family meeting after the parents' deaths, three children not working in the business wanted to know how much income they'd begin getting from the business. The two brothers who worked in the business contended they had to sell it to pay estate taxes.

The business was shut down and sold at a huge discount. The two brothers opened a new, but less successful, business, recalls Ciepiela. All of that could have been avoided if the parents had bought life insurance to cover estate taxes or equalize the distribution to children who didn't work in the business.

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