The feds are investigating whether Donald Trump’s longtime lawyer and self-described fixer Michael Cohen cheated on his taxes, according to a report Tuesday.

Federal authorities are probing whether Cohen’s income from his taxi medallion business was under-reported in his federal tax returns, the Wall Street Journal reported, citing sources.

That income included hundreds of thousands of dollars he got in cash and other payments over the past five years, the paper said.

Prosecutors are also investigating whether any employees of banks that loaned Cohen money didn’t require him to submit proper documentation.

Cohen’s relationship with Sterling National Bank — which provided financing for Cohen’s taxi medallion business — is also under the microscope.

Tax fraud charges would ramp up the pressure on Cohen, who has already shown signs that he could cooperate with special counsel Robert Mueller’s probe into Russian election interference and potential collusion with Trump’s campaign, including his son Don Jr.

Cohen reportedly suggested that Trump knew in advance about the infamous June 2016 Trump Tower meeting that his son, son-in-law Jared Kushner and then-campaign chair Paul Manafort had with a Kremlin-connected Russian lawyer offering to dish dirt on Hillary Clinton. The president denied that he knew about the sit-down.

Cohen’s lawyer, former Clintonista Lanny Davis, declined to comment “out of respect for the ongoing investigation,” the Journal reported.

The FBI and the Manhattan US Attorney’s Office are also investigating Cohen for bank fraud, campaign finance violations and other possible crimes related to his efforts to cover up alleged sex scandals involving Trump, including a $130,000 payment to porn queen Stormy Daniels.

The president denied having sex with Daniels and another woman, former Playboy pin-up Karen McDougal, who, like Daniels, charged that she had sex with Trump in 2006 when his third wife, Melania, was caring for their recently born son.