Le Canard Enchaine newspaper reported Wednesday that Penelope Fillon earned the money over eight years as a parliamentary aide to her husband during his tenure as a lawmaker.
It's not illegal for French legislators to hire their relatives as long as they are genuinely employed.
Fillon's spokesman Philippe Vigier denied any wrongdoing, insisting that Penelope Fillon's work wasn't fictional.
Fillon, a former prime minister, has been designated as the conservative presidential nominee. Opinion polls suggest that he and far-right leader Marine Le Pen will advance to the second round of the election later this year.