Donald Trump
President Donald Trump delivers his first address to a joint session of Congress from the floor of the House of Representatives in Washington, Feb. 28, 2017. Reuters

President Donald Trump apparently has a flair for exaggeration when it comes to how rich he actually is. Last May, Trump claimed he earned nearly $21 million through New York City contracts to run two skating rinks in Central Park and a golf course in the Bronx. But he actually earned half of that $21 million at most, found an investigation from non-profit news site ProPublica Wednesday.

When running for president, Trump played up his persona as a successful businessman and real estate magnate who would both create jobs and bolster government efficiency by cutting out unnecessary bureaucratic regulations. However, it has been impossible to confirm Trump’s claims, as he’s refused to release his tax returns — the first president to do so in the past 40 years.

Wednesday wasn't the first time journalists have uncovered evidence that Trump has exaggerated his income. In May, Fortune and Forbes discovered that Trump may have intentionally misrepresented his gross receipts as his net income.

What does that mean in plain English? Take a hypothetical situation: If Trump were running a lemonade stand instead of skating rinks, he may have made $21 one week. That’s his gross income. But he had to pay for the lemons, the sugar and the pitcher — say, $10 in total. Those are the expenses. In the end, he didn’t really make $21 because he had to pay for all of his ingredients. Instead, he made $11. That’s his net income.

When Trump submitted the listing of his financial holdings to the U.S. Office of Government Ethics, he reported his income as $21 million. But he did not disclose his expenses, and that $21 million could have been intentionally misrepresented as his net income rather than his gross income.

“It’s sufficiently ambiguous that, while Trump may meet their reporting requirements, it’s really misleading,” said Virginia Canter, who was an associate counsel for ethics in the Clinton and Obama administrations and ethics adviser for the International Monetary Fund.

View full documents of Trump's contracts with New York City here.