"There is nothing to learn from them," Presidential candidate Trump said at the time, referring to a tax audit of his activities.

Around the same time, New York Times journalist Susanne Craig and colleagues began trying to find tax returns in other ways.

They have made several revelations on the subject in recent years, but tonight's revelation is - for the president - the most serious so far.

This is how the revelation is summarized

The revelation, the first of several according to the New York times, is based on two decades of tax documents that the newspaper has had access to.

The report is over 60,000 characters long but can be summarized in some particularly important points.

  • The president paid about $ 7,000 in federal income tax the year he became president and the first year in the White House.

    Trump paid zero dollars in federal income tax 10 of the previous 15 years.

  • A whole host of Donald Trump companies, from golf courses to hotel licensing companies, have made huge losses over the years, something that has given Trump the opportunity to get tax rebates and reimbursements in the millions.

  • The tax audit that is currently underway may force the president to pay back up to SEK 900 million in taxes and interest to the US Tax Agency, after he received a dubious tax refund of over SEK 650 million in connection with the financial crisis.

  • Donald Trump has a loan of SEK 2.7 billion which he is personally liable for and for which he will have to repay in the next few years.

Why does this matter?

The image of Donald Trump as a successful businessman has proven to be very important to the president.

The American people trust Joe Biden more than Donald Trump in dealing with the corona virus and a number of other issues.

But Americans trust Trump as much or more than Biden when it comes to managing the economy.

Rocket fuel for the Biden campaign

In an election where the economy is the single most important issue for voters, the revelation from the New York Times' rocket fuel for the Biden campaign.

More or less immediately, Trump critics are beginning to produce television advertising campaigns about Donald Trump's "scam" or start calls on social media where everyone who paid more in federal income tax than Donald Trump is offered to participate.

That is why it is now important for the president to defend himself.

He has done the same.

Trump went out and called the revelation "fake news".

He stated on Sunday that he "paid lots and paid lots in income tax to the state as well".

A lawyer for the Trump organization also states that the New York Times' revelation is "full of gross inaccuracies" and that Trump has "paid tens of millions of dollars in personal taxes to federal authorities over the past decade."

The New York Times points out, however, that the lawyer in his response seems to have merged Trump's federal income taxes with other taxes, such as social security contributions and employer contributions for employees of Trump's households.

How much the revelation, and more possible similar revelations, will affect the election is not easy to predict.

The vast majority of voters have already decided who they want to vote for, and traditionally the televised debates give rise to greater movements in the electorate than individual revelations.

But there are exceptions, and it is clear that Donald Trump - who is still struggling to catch up with Biden in opinion polls - is not likely to get help with such revelations about his holy grail - the image of him as a successful businessman.