Supplemental Needs Trust - A legal tool used to help disabled people keep more of their income or assets without losing their public benefits. The technical definition is that they are irrevocable, spendthrift trusts that comply with the provisions of 42 U.S.C. § 1396p(d)(4). There are two types: individual SNTs and pooled SNTs. An SNT can also be a third-party trust, where the money is provided by someone other than the beneficiary.