A beneficial interest is the right that a person has arising from a contract to which they are not a party, or a trust.
[1] For example, if A makes a contract with B that A will pay C a certain sum of money, B has the legal interest in the contract, and C the beneficial interest.
[2] More specifically, it could be: Black's Law Dictionary defines beneficial interest as "Profit, benefit or advantage resulting from a contract, or the ownership of an estate as distinct from the legal ownership or control.
"[3][4] Examples of beneficial interests in mining claims include unrecorded deeds and agreements to share profits, but not mortgages and other liens.
[5] A beneficial interest is also "distinguished from the rights of someone like a trustee or official who has responsibility to perform and/or title to the assets but does not share in the benefits".