The New York Times has obtained tax-return data extending over more than two decades for Mr. Trump and the hundreds of companies that make up his business organization, including detailed information from his first two years in office. It does not include his personal returns for 2018 or 2019. This article offers an overview of The Times’s findings; additional articles will be published in the coming weeks.

Based on the financial disclosures, which report much of his income in broad ranges, Mr. Trump’s earnings from the Istanbul towers could have been as low as $3.2 million. In the Philippines, where he licensed his name to a Manila tower nearly a decade ago, the low end of the range was $4.1 million — less than half of the $9.3 million he actually made. In Azerbaijan, he collected more than $5 million for the failed hotel project, about twice what appeared on his public filings.

It did not take long for conflicts to emerge when Mr. Trump ran for president and won. The Philippines’ strongman leader, Rodrigo Duterte, chose as a special trade envoy to Washington the businessman behind the Trump tower in Manila. In Argentina, a key person who had been involved in a Uruguayan licensing deal that earned Mr. Trump $2.3 million was appointed to a cabinet post.

The president’s conflicts have been most evident with Turkey, where the business community and the authoritarian government of President Recep Tayyip Erdogan have not hesitated to leverage various Trump enterprises to their advantage. When Turkish-American relations were at a low point, a Turkish business group canceled a conference at Mr. Trump’s Washington hotel; six months later, when the two countries were on better terms, the rescheduled event was attended by Turkish government officials. Turkish Airlines also chose the Trump National Golf Club in suburban Virginia to host an event.

More broadly, the tax records suggest other ways in which Mr. Trump’s presidency has propped up his sagging bottom line. Monthly credit card receipts, reported to the I.R.S. by third-party card processing firms, reflect the way certain of his resorts, golf courses and hotels became favored stamping grounds, if not venues for influence-trading, beginning in 2015 and continuing into his time in the White House.

What’s more, the tax records show that Mr. Trump has once again done what he says he regrets, looking back on his early 1990s meltdown: personally guaranteed hundreds of millions of dollars in loans, a decision that led his lenders to threaten to force him into personal bankruptcy.

This time around, he is personally responsible for loans and other debts totaling $421 million, with most of it coming due within four years. Should he win re-election, his lenders could be placed in the unprecedented position of weighing whether to foreclose on a sitting president.