He is to be sentenced for lying to Federal Bureau of Investigation in a case stemming from the investigation into possible collusion between President Donald Trump’s campaign team and Russia in 2016 election-run-up.
US District Judge Emmet Sullivan will sentence Flynn in Washington at 11am ET (1600 GMT).
Special Prosecutor Robert Mueller, who is leading the investigation into Russian interference, has asked Sullivan not to imprison Flynn.
Flynn is a former general, because of his military service and because he provided “substantial” cooperation with the probe Sullivan makes a plea for him.
Flynn pleaded guilty in December 2017 to lying to FBI agents about his conversations with Sergei Kislyak, Russia ambassador in Washington at the time.
Flynn told investigators in January 2017 that he had not discussed US sanctions against Russia with Kislyak, when in fact he had, according to his plea agreement.
Lying to the FBI carries a statutory maximum sentence of five years in prison.
Flynn’s plea agreement states that he is eligible for a sentence of between zero and six months, however, and can ask the court not to impose a fine.
Flynn’s lawyers have asked the court for a probation term of no more than one year, with minimal conditions of supervision, and 200 hours of community service.
Flynn also deserves leniency because he was not warned before the meeting with FBI agents that it was a crime to lie to them, his lawyers said in a recent court filing.
They also said that then-FBI Deputy Director Andrew McCabe had told Flynn that the “quickest way” to conduct the interview was without counsel present.
Critics of the Mueller probe argue that Flynn, who held the White House job for only 24 days, was set up.
Mueller last week countered in a court filing that Flynn had no cause to lie in the interviews.
He added that a “sitting National Security Adviser, former head of an intelligence agency, retired Lieutenant General, and 33-year veteran of the armed forces knows he should not lie to federal agents.”
Flynn is so far the only member of Trump’s administration to plead guilty to a crime uncovered during Mueller’s wide-ranging probe.
The probe has so far ensnared 32 individuals and three Russian firms.
Trump denies there was any collusion and has labelled the investigation a “witch hunt.”
Russia also denies it meddled in the election, contrary to the conclusion of US intelligence agencies.
On Monday, Sullivan ordered the special counsel to release a redacted, five-page FBI account of Flynn’s January 2017 interview, saying it was relevant to his sentencing.