TOKYO—Carlos Ghosn received tens of millions of dollars in deferred compensation at Nissan Motor Co. and told colleagues he was acting appropriately when he didn’t report that money in financial disclosures, people familiar with Nissan’s investigation said.

The new information suggests a possible line of defense emerging for Mr. Ghosn, who was arrested Nov. 19 in Tokyo on suspicion of underreporting his income in financial statements by ¥5 billion, or about $44 million, over five fiscal years ended March 2015.