In President Trump’s telling, he is a committed philanthropist with strong ties to many charities. “If you don’t give back, you’re never ever going to be fulfilled in life,” he wrote in “Trump 101: The Way to Success,” published at the height of his “Apprentice” fame.

And according to his tax records, he has given back at least $130 million since 2005, his second year as a reality TV star.

But the long-hidden tax records, >obtained by The New York Times, show that Mr. Trump did not have to reach into his wallet for most of that giving. The vast bulk of his charitable tax deductions, $119.3 million worth, came from simply agreeing not to develop land — in several cases, after he had shelved development plans.

Three of the agreements involved what are known as conservation easements — a maneuver, popular among wealthy Americans, that typically allows a landowner to keep a property’s title and receive a tax deduction equal to its appraised value. In the fourth land deal, Mr. Trump donated property for a state park.

The New York attorney general is investigating whether the appraisals on two of Mr. Trump’s easement donations were improperly inflated to win larger tax breaks, according to court filings.

Mr. Trump’s pronouncements of philanthropic largess have been broadly discredited by reporting, most notably in The Washington Post, that found he had exaggerated, or simply never made, an array of claimed contributions. His own charitable foundation shut down in 2018 amid allegations of self-dealing to benefit Mr. Trump, his businesses and his campaign.

But the tax data examined by The Times lends new authority and far greater precision to those findings. The records, encompassing his reported philanthropic activity through 2017, reveal not only its exact dimensions; they show that much of his charity has come when he was under duress — facing damage to his reputation or big tax bills in years of high income.

Of the $7.5 million in business and personal cash contributions reported to the Internal Revenue Service since 2005, more than 40 percent — $3.2 million — came starting in 2015, when Mr. Trump’s philanthropy fell under scrutiny after he announced his White House bid. In 2017, his first year in office, he declared $1.9 million in cash gifts. In 2014, by contrast, he contributed $81,499.

And his first two land-easement donations were made in what the tax records show was a period of significant taxable income — 2005 and 2006, prime time for his reality TV fame.

The president’s Trump Organization biography says he is “involved with numerous civic and charitable organizations.” When he announced his campaign in 2015, he said he had given more than $102 million to charity over the previous five years.

While it is possible that he chose not to report some of his giving, his tax records for 2010 to 2014 reflect far less than he claimed — $735,238 in cash and $26.8 million in land easements and other noncash gifts. Six months into the campaign, in December 2015, another easement, valued at $21.1 million, was completed.

In response to questions from The Times, Amanda Miller, a spokeswoman for the Trump Organization, said: “President Trump gives money privately. It’s impossible to know how much he’s given over the years.”

The tax information analyzed by The Times includes annual totals for business and individual giving but lists only certain corporate donations.

The single largest cash donation he reported for his businesses, made to his own foundation, was the $400,000 he received in 2011 for being roasted on Comedy Central. In 2014, his Virginia winery contributed a glass sculpture valued at $73,600 to a small historical society in Pennsylvania. And in 2016, another one of his companies gave $30,000 to the American Hotel & Lodging Education Foundation.

Even without the details of Mr. Trump’s individual giving, The Times was able to identify public philanthropic promises that appear either to have been exaggerated or to have never materialized. In each case, the size of his pledge exceeded what he told the I.R.S. he had given in a particular year. 

In 2009, for example, he agreed to rent his Seven Springs estate in Westchester County, N.Y., to the Libyan dictator Col. Muammar el-Qaddafi, who hoped to stay in a tent on the grounds during a meeting of the United Nations General Assembly.

Though the plans fell apart when local residents objected, Colonel Qaddafi made a payment of $150,000, which Mr. Trump told CNN in 2011 that he had given to charity. His 2009 tax returns, however, reported only $22,796 in business and personal cash gifts.

In 2015, Mr. Trump promised to donate the earnings from his book “Crippled America: How to Make America Great Again.’’

“The profits of my book? I am giving them away to a lot of different — including the vets,” he said at a news conference.

The tax records show that Waxman Leavell Literary Agency, which represented Mr. Trump’s book, made two payments to him in 2015 and 2016, totaling roughly $4.5 million. In those years, Mr. Trump reported giving a total of $1.3 million in cash to charity.