The phrase "be owing" can be expressed in multiple ways using synonyms. One could say that something is "due," which implies a sense of obligation or expectation. Another synonym is "owing," which is a direct replacement for the original phrase. "In arrears" could also be used to describe something that is overdue or has been neglected. Additionally, "owing to" could be used to say that something is due to a certain circumstance or situation. Other possible synonyms for "be owing" include "unpaid," "outstanding," and "owing money." By using these synonyms, one can vary their language and make their writing more interesting and engaging.