"Getting remarried ... Oh, what fun when it comes to estate planning," said certified financial planner Mark LaSpisa, president and managing advisor of Vermillion Financial Advisors.
"The biggest challenge is, how does anyone reconcile preserving assets for children from a prior marriage while taking care of one's commitment to a new spouse?" he said.
LaSpisa recommends thinking ahead and considering questions such as what your goals are, how your existing family and new spouse will relate to one another once you've passed away, and who will be in charge of the money.
"The fundamental issue is that the heirs of a couple remarrying have more to fear from the new spouse than from the federal estate-tax collectors," said lawyer lawyer John J. Scroggin, an accredited estate planner and partner with Roswell, Georgia-based law firm Scroggin & Co. He gives some examples of why:
The ex-spouse may still be involved, too, said Susan Green, lawyer and certified financial planner with Wescott Financial Advisory Group. "Assets could still be left to your ex-spouse if you have not updated your beneficiary designations, even if your intent was to provide for your new spouse and/or children instead," she said.
Beware that you might be contractually obligated to keep your ex-spouse as beneficiary of a retirement account or life insurance policy for a certain period of time, Green added.
Green offered some issues to consider when updating estate-planning documents:
Therese R. Nicklas, CFP and wealth manager with U.S. Wealth Management, said other common mistakes include not taking new home-state laws into consideration if a couple remarries and moves out of state and, if the couple owns multiple properties, not titling them into the plan (if a trust is involved).
Common estate-planning mistakes after remarrying
Source: Mark LaSpisa, president and managing advisor of Vermillion Financial Advisors
"Rewriting a plan is normally not too complicated unless your former plan includes an irrevocable trust," she said. "Having trusted advisors [e.g., an estate-planning attorney, financial advisor and CPA] walk you through in a step-by-step manner can help you avoid many pitfalls.
"What one advisor might overlook, the other will pick up, helping you avoid having significant details fall through the cracks."
Nicklas added that although you may have to pay for these professionals' time, good advice and guidance can save you money in the long term. "Mistakes made by not planning properly often have costs that cannot be measured," she said.
— By Deborah Nason, special to CNBC.com