When is the corporation estopped to deny ratification of contracts or acts entered by its officers or agents?

Generally, when the corporation has knowledge that its officers or agents exceed their power, it must promptly disaffirm the contract or act, and allow the other party or third person to act in the belief that it was authorized or has been ratified. Otherwise, if it acquiesces, with knowledge of the facts, or if it fails to disaffirm, ratification will be implied. (Premiere Development Bank vs. CA, G.R. No. 159352, Apr. 14, 2004)