A person who, because of his or its relationship with the plan (i.e. as a fiduciary, as a provider of services, as the plan sponsor) is prohibited from entering into certain transactions with the plan.
A party to the plan who is not a fiduciary, but has knowledge of and interest in the plan. A TPA is a party in interest.
An ERISA-specified individual—such as an administrator, officer, fiduciary, trustee, custodian, or counsel—who is prohibited from making certain transactions involving a retirement plan. A trustee, for example, would be prohibited from using an IRA as collateral for a loan.
Under ERISA's 2002 Modernization Act: Parties in interest include employers, unions and, in certain circumstances, fiduciaries. It excludes service providers and their affiliates. Fiduciaries would only be parties in interest where they act on behalf of a plan sponsor in entering into a transaction. An affiliate of a party in interest does not include remote affiliates of employers, unions and fiduciaries (e.g., 10 percent owners), as well as employees of such remote affiliates. [Go to source
A party that, because of his, her, or its special relationship with the plan (e.g., as a fiduciary, provider of services, or the plan sponsor), is prohibited from entering into certain transactions with the plan.
Per the Department of Labor, any person or entity prohibited by ERISA from entering into certain transactions with a qualified plan, unless the transaction is permitted by a statutory or administrative exemption.