When New York prosecutors lastly get to look at the federal tax returns of former President Donald J. Trump, they are going to uncover a veritable how-to information for getting wealthy whereas dropping hundreds of thousands of {dollars} and paying little to no revenue taxes.

Whether or not they discover proof of crimes, nevertheless, can even depend upon different data not discovered within the precise returns.

The United States Supreme Court on Monday cleared the best way for the Manhattan district legal professional, Cyrus R. Vance Jr., to acquire eight years of Mr. Trump’s federal revenue tax returns and different information from his accountants. The choice capped a long-running authorized battle over prosecutors’ entry to the knowledge.

The New York Occasions final yr offered kind of a preview of what awaits Mr. Vance, when it obtained and analyzed decades of income tax data for Mr. Trump and his firms. The tax information present an unprecedented and extremely detailed have a look at the byzantine world of Mr. Trump’s funds, which for years he has concurrently bragged about and sought to maintain secret.

The Occasions’s examination confirmed that the previous president reported a whole bunch of hundreds of thousands of {dollars} in enterprise losses, went years with out paying federal revenue taxes and faces an Inner Income Service audit of a $72.9 million tax refund he claimed a decade in the past.

Amongst different issues, the information revealed that Mr. Trump had paid simply $750 in federal income taxes in his first yr as president and no revenue taxes in any respect in 10 of the earlier 15 years. Additionally they confirmed he had written off $26 million in “consulting charges” as a enterprise expense between 2010 and 2018, a few of which seem to have been paid to his older daughter, Ivanka Trump, whereas she was a salaried worker of the Trump Group.

The legitimacy of the charges, which diminished Mr. Trump’s taxable revenue, has since become a subject of Mr. Vance’s investigation, in addition to a separate civil inquiry by Letitia James, the New York legal professional normal. Ms. James and Mr. Vance are Democrats, and Mr. Trump has sought to painting the a number of inquiries as politically motivated, whereas denying any wrongdoing.

Mr. Vance’s workplace has issued subpoenas and performed interviews in current months because it scrutinizes a variety of financial matters, together with whether or not the Trump Group misrepresented the worth of belongings when acquiring loans or paying property taxes, in addition to the fee of $130,000 in hush cash through the 2016 marketing campaign to Stephanie Clifford, the pornographic movie actress whose stage identify is Stormy Daniels. Amongst these interviewed have been staff of Deutsche Financial institution, certainly one of Mr. Trump’s largest lenders.

For all their revelations, Mr. Trump’s tax information are additionally noteworthy for what they don’t present, together with any new particulars in regards to the fee to Ms. Clifford, which was the preliminary focus of Mr. Vance’s investigation when it started two years in the past.

The tax returns characterize a self-reported accounting of revenues and bills, and sometimes lack the specificity required to know, for example, if authorized prices associated to hush-money funds had been claimed as a tax write-off, or if cash from Russia ever moved by Mr. Trump’s financial institution accounts. The absence of that stage of element underscores the potential worth of different information that Mr. Vance gained entry to with Monday’s Supreme Courtroom choice.

Along with the tax returns, Mr. Trump’s accountants, Mazars USA, should additionally produce enterprise information on which these returns are primarily based and communications with the Trump Group. Such materials might present necessary context and background to selections that Mr. Trump or his accountants made when making ready to file taxes.

John D. Fort, a former chief of the I.R.S. prison investigation division, mentioned tax returns had been a great tool for uncovering leads, however might solely be absolutely understood with extra monetary data obtained elsewhere.

“It’s a really key private monetary doc, but it surely’s only one piece of the puzzle,” mentioned Mr. Fort, a C.P.A. and the director of investigations with Kostelanetz & Fink in Washington. “What you discover within the return will should be adopted up on with interviews and subpoenas.”

Nonetheless, The Occasions’s investigation of Mr. Trump’s returns uncovered numerous deceptive assertions and falsehoods he has propagated about his wealth and enterprise acumen.

Quite a few claims by Mr. Trump of beneficiant philanthropy fell aside upon examination of his tax returns, which raised questions on each the quantity of sure donations and the general nature of his tax-deductible giving. For instance, $119.3 million of the roughly $130 million in charitable deductions he claimed since 2005 turned out to be the estimated worth of pledges to not develop actual property, typically after a deliberate challenge fell by.

A minimum of two of these land-based charitable deductions, one associated to a golf course in Los Angeles and the opposite a Westchester property known as Seven Springs, are identified to be a part of the civil inquiry by Ms. James, who’s analyzing whether or not value determinations supporting the tax write-offs had been inflated.

Extra broadly, the tax information confirmed how the general public disclosures he filed as a candidate after which as president supplied a distorted view of his general funds by reporting glowing numbers for his golf programs, lodges and different companies primarily based on the gross revenues they collected every year. The precise backside line, after losses and bills, was a lot gloomier: In 2018, whereas Mr. Trump’s public filings confirmed $434.9 million in income, his tax returns declared a complete of $47.4 million in losses.

And such dire numbers weren’t an anomaly. Mr. Trump’s many golf programs, a core element of his enterprise empire, reported losses of $315.6 million from 2000 to 2018, whereas the revenue from licensing his identify to lodges and resorts had all however dried up by the point he entered the White Home. As well as, Mr. Trump has a whole bunch of hundreds of thousands of {dollars} in loans, a lot of which he personally assured, coming due within the subsequent few years.

The Occasions’s investigation additionally discovered that he faces a doubtlessly devastating I.R.S. audit specializing in the large refund he claimed in 2010, which lined all of the federal revenue taxes he paid from 2005 to 2008, plus curiosity. Mr. Trump repeatedly cited the continued audit as the rationale he couldn’t launch his tax returns, after initially saying he would, regardless that nothing in regards to the audit course of prevented him from doing so.

If an I.R.S. ruling had been to finally go in opposition to him, Mr. Trump might be pressured to pay again greater than $100 million, factoring in curiosity and attainable penalties, along with some $21.2 million in state and native tax refunds that had been primarily based on the figures in his federal filings.

Russ Buettner and Susanne Craig contributed reporting.