Donald Trump used a tax avoidance maneuver so "legally dubious" that his own lawyers advised him the Internal Revenue Service would consider it improper, the New York Times (NYT) reports.

The NYT said it had newly obtained documents related to the Republican presidential candidate's tax affairs from the 1990s—a time at which Trump was attempting to stave off financial ruin as several of his casinos went bust—that shows he potentially swapped canceled debt held by the bankrupt gaming houses for "partnership equity."

The newspaper previously reported that Trump declared a $916 million loss on his tax returns in 1995, which would have allowed him to cancel out an equivalent amount of taxable income over the next 18 years.

It said such a debt-for-equity swap was likely vital to allowing Trump to keep the tax benefit of that huge loss. Although the NYT's main report implies strongly but does not specifically say that Trump undertook the tax avoidance maneuver, an accompanying interactive graphic alleges that he did.