After the two prison sentences for Paul Manafort were added up Wednesday, they totaled 7½ years. But Manafort probably will spend less than 6½ years behind bars if he behaves.

Because he has been in jail for nine months, he’s likely to be released no later than December 2024.

That’s if he does not draw an additional sentence in state court in New York, where he was indicted Wednesday on mortgage fraud and other charges. If he is convicted, a New York judge would decide whether that time would be served concurrently with or after his federal time.

Manafort’s two related federal criminal cases — in the District and Virginia — have brought attention to the complexities of federal court sentencing. Now that the full punishment is known for President Trump’s onetime campaign chairman, another set of rules govern how that term is calculated.

If Trump pardons Manafort from his federal convictions and sentences, the New York case could still proceed.

There is no parole in federal sentencing, but inmates can receive 54 days of “good time” credit for every full year they serve, if they cause no problems. For Manafort, that means his total 7½ -year sentence could be reduced by 378 days, meaning his actual time served would be about six years and five months.

But there are more ways to reduce a federal sentence, experts said, and Manafort may benefit from changes enacted in the recently passed First Step Act, said Douglas Berman, a law professor at Ohio State University. One of those changes was in the 54-day “good time” credit. For some years, the federal Bureau of Prisons had reduced that to 47 days per year, but the First Step Act mandates that the reduction be restored to 54 days, Berman noted.

Another way to shave time off a sentence is to enter the Residential Drug Abuse Program in a federal prison. For those who show they had a prior drug or alcohol program and complete a nine-month program, up to a year in prison can be taken off a sentence, Bureau of Prisons officials said.

Manafort is not known to have a drug or alcohol problem.

About 15,600 inmates enrolled in the residential drug program in 2018, federal prison statistics show, but the number has steadily dropped since 2015, when 18,300 inmates were enrolled.

A third sentence-reduction path, available to older inmates such as Manafort, 69, is the Elderly Offender Home Detention program, first tried in 2009 and relaunched by the First Step Act this year. It allows for inmates who are over 60 and have served two-thirds of their total sentence to be released to home confinement, said John B. Webster, a Nashville prison and sentencing consultant. The Bureau of Prisons determines who may be released and their decision cannot be appealed, Webster said.

The First Step Act also expanded the age eligibility of elderly offenders from 65 to 60 years old, the minimum time served from 75 percent to 66 percent of a sentence, and extended the release program to all federal prisons.

If Manafort’s health deteriorates further, he could become eligible for the “compassionate release” program, in which inmates who are seriously ill are released to receive more intensive medical treatment. In 2013, defense lawyer Lynne Stewart was released from prison after serving four years of a 10-year sentence for conspiracy and providing aid to terrorists, because she had breast cancer.

Until this year, when the First Step Act enabled inmates to make such an appeal to the courts if the Bureau of Prisons refused, only prison officials could recommend such a release.

Less than 3 percent of the 180,438 inmates currently in the federal system are 65 or older, prison statistics show. Slightly more than 25 percent of federal prisoners are serving terms of five to 10 years, and 21 percent are serving 10 to 15 years. Sixty-two federal inmates are facing a death sentence.

The First Step Act may provide another option for sentence reduction for Manafort that does not exist yet. The measure calls for the creation of a risk assessment tool that would enable the Bureau of Prisons to move prisoners to halfway houses or other external facilities sooner, and to create programs that would allow inmates to earn credit toward earlier release.

The Trump administration has not yet created the committee that would devise these programs and options. But it could occur during Manafort’s time in prison.

Also, prosecutors could file a motion seeking a sentence reduction for Manafort at any time during his sentence if he provides substantial assistance with other criminal investigations. Prosecutors in Washington last month requested an early release for drug kingpin Rayful Edmond Jr., who is serving a life sentence without parole, because of information he has provided authorities in drug and prison cases. The judge in Edmond’s case has not ruled on the government’s motion.

This story has been updated to clarify the types of early release programs that may be available to Manafort.