(Image credit: Getty Images) For families with a child or grandchild who has special needs, a properly drafted special needs trust (SNT) can be one of the most powerful planning tools available. It can preserve eligibility for government benefits, provide supplemental support and create long-term financial stability . But there's a mistake I see far too often — one that can quietly undermine everything a family is trying to accomplish: Naming a special needs trust as the beneficiary of tax-deferred retirement accounts. From just $107.88 $24.99 for Kiplinger Personal Finance Become a smarter, better informed investor. Subscribe from just $107.88 $24.99, plus get up to 4 Special Issues CLICK FOR FREE ISSUE Sign up for Kiplinger’s Free Newsletters Profit and prosper with the best of expert advice on investing, taxes, retirement, personal finance and more - straight to your e-mail. Profit and prosper with the best of expert advice - straight to your e-mail. At first glance, it seems logical.…