2020 presidential candidate Sen. Bernie Sanders (I-VT) said in a recent interview that lucrative book sales made him a millionaire, and he will release his tax returns next Monday.

“On the day in the very immediate future, certainly before April 15, we release ours, I hope that Donald Trump will do exactly the same,” Sanders told the New York Times.

“We are going to release 10 years of our tax returns, and we hope that on that day Donald Trump will do the same,” he added.

The 77-year-old democratic-socialist also acknowledged his cushy financial situation, pointing to his New York Times best-seller Where We Go From Here, published in November 2018, as the reason for his 1 percenter status.

“I wrote a best-selling book. If you write a best-selling book, you can be a millionaire, too,” he quipped.

In an interview last week, Sanders campaign manager Faiz Shakir said the senator and his wife, Jane, wanted to finish their 2018 taxes first before releasing their returns. The Times reported Sanders’ 2017 Senate financial disclosure forms show he raked in around $1.06 million that year. The Vermont lawmaker owns three houses, one of which he purchased in 2016 for $575,000. The four-bedroom lake-front property in North Hero, Vermont, boasts 500 feet of Lake Champlain beachfront, according to newspaper Seven Days. Sanders also owns homes in Burlington, Vermont, and Washington, D.C.

During his first presidential bid, Sanders endured questioning by Hillary Clinton over why he had not released several years of his tax returns and had instead opted to release just his 2014 tax returns.

Several of Sanders’ rivals for the Democratic presidential nomination have already released their 2018 tax returns. Sens. Elizabeth Warren (D-MA), Amy Klobuchar (D-MN), and Kirsten Gillibrand (D-NY) have all released their own returns.

The Associated Press contributed to this report.