An asset management company belonging to billionaire Yusaku Maezawa, founder of online clothing store Zozotown, failed to declare about ¥500 million ($4.6 million) in taxable income, sources close to the matter said.

After underreporting income over three years through March 2019, Maezawa's company corrected its tax report as pointed out by the Tokyo Regional Taxation Bureau but paid no additional levies as the undeclared income had been offset by losses, they said Wednesday.

The 44-year-old businessman, who has grabbed attention in recent years for his luxurious lifestyle, also failed to report as much as ¥99 million in personal income over the three years through 2018 he is believed to have earned from selling paintings, the sources said.

But the former fashion entrepreneur later amended his declaration, with the additional tax and penalty fees totaling about ¥40 million.

According to the sources, Maezawa is believed to have paid usage fees for a private jet owned by his asset management firm in Tokyo's Minato Ward for personal travel. The Tokyo bureau has deemed the amount paid was insufficient and the shortfall thus constituted the company's failure to declare income.

In a YouTube video last December, Maezawa said, "It has been nearly four years since the purchase of the jet. I use it a lot as it is convenient."

On Wednesday, Maezawa tweeted, "I will neither hide nor escape. If the tax office points out anything in the way the taxes have been handled, I will not hesitate to pay the taxes so please use them wisely."

Maezawa stepped down last year as CEO of Zozo Inc. He grabbed global attention when he was named by U.S. tech billionaire Elon Musk's SpaceX as the first private passenger for a planned flight around the moon.