in interest

in one's (own) (best) interest(s)

to one's advantage; as a benefit to oneself. It is not in your own interests to share your ideas with Jack. He will say that they are his. Jane thought it was in the best interest of her friend to tell his mother about his illness.
See also: interest
References in periodicals archive ?
Life insurers began to ratchet up crediting rates on interest-sensitive policies in 2006, with a moderation in interest rate spreads.
Steve has a degree in mathematics from Queen Mary College, University of London, and over 20 years experience in interest rate derivatives and IT.