he was informed -- Past Indefinite Passive Voice he has been informed - Present Perfect Passive Voice each is used for expressing it's own meaning

Basically, "he was informed" is just a statement that in the past, someone informed him. "He has been informed" talks about the present as a result of something that happened in the past. In other words, it means that right now he is informed because he was informed in the past. So the first one is correct, because as Neil explained the action occurred at a single point in time. Also, "is" should be "was". If you want to make the second sentence grammatically correct, you'd have to change 'have' to 'had' ("Upon checking with Finance, he HAD been informed that the cheque was not ready"), although this means something completely different. It means that by the time he was checking with finance, he had already been informed about the cheque.

The first is correct. Upon checking with finance occured once, at a single point in time. Therefore, the informing occured only once. Has been could potentially occur only once, but to me, it indicates that occured before the checking. This example might work: Every time he has checked with finance, he has been informed that the cheque is not ready

Upon checking with Finance, he was informed that the cheque was (not is) not ready After checking with Finance, he has been informed that the cheque is not ready Both are correct, it depends what you are trying to say.