Not paying is a phrase that indicates a failure to fulfill a financial obligation. There are several synonyms for this phrase that can be used depending on the context. One synonym is defaulting, which specifically refers to a failure to pay a debt. Another synonym is disregarding, which suggests a lack of interest in fulfilling an obligation. Another possible synonym is neglecting, which implies a responsibility has been overlooked or disregarded. Similarly, the phrase ignoring a bill or refusing to pay also convey the same meaning as not paying. Using these synonyms can add variety and depth to communication while conveying the same underlying idea.