US lawmakers released Donald Trump's tax returns on Friday, ending a yearslong battle by the former president to keep his finances private as he prepares for another run at the White House in 2024.

The Republican leader -- who lost his re-election bid as he served a single term from 2017-2021 -- broke with tradition by refusing to release the records, triggering feverish speculation about what they might contain.

The House Ways and Means Committee released a summary earlier in December of six years of filings, from 2015 to 2020, as part of investigations into the presidential audit program.

The documents showed that Trump wasn't being regularly audited by the Internal Revenue Service (IRS) and that, despite reporting millions in earnings, he paid little in tax by claiming large business losses.

"The 'Trump' tax returns once again show how proudly successful I have been and how I have been able to use depreciation and various other tax deductions as an incentive for creating thousands of jobs and magnificent structures and enterprises," Trump said in a written statement to CBS News.

The returns themselves released Friday were not expected to yield sensational new revelations, but Democrats hope they will add detail on Trump's businesses and particularly any foreign concerns that might present conflicts of interest.

"In terms of high-end product influx into the US, Russians make up a pretty disproportionate cross-section of a lot of our assets," the former president's eldest son, Donald Trump Jr, is reported to have told a New York real estate conference in 2008.

"Say, in Dubai, and certainly with our project in SoHo, and anywhere in New York. We see a lot of money pouring in from Russia."

The House Ways and Means Committee voted on December 20 to release all of Trump's 2015-2020 returns, ending a four-year battle between Democrats and the former president that eventually reached the Supreme Court.

The summary showed that the 76-year-old billionaire mostly claimed enormous annual deficits.

He paid $1.1 million in federal taxes in 2018 and 2019, the middle two years of his presidency, after making around $30 million selling assets.

But that dwarfed his $750 bill in 2017 -- and he paid nothing at all as his losses mounted in 2020.

The report also showed that Trump had carried forward $105 million in net operating losses on his 2015 return, $73 million in 2016, $45 million in 2017 and $23 million in 2018 to reduce his tax liability.

The New York Times alleged in 2020 that Trump had paid no income tax in 10 of the previous 15 years after reporting massive losses.

A separate congressional report on the IRS's mandatory presidential audit program showed it was not doing its job during most of Trump's time in office.

"The IRS only opened one mandatory examination from 2017 to 2020 for returns filed while the former president was in office," the report reads.

The IRS began to audit Trump on the very day that Ways and Means Democrats requested his tax information in 2019.