Maryland Gov. Larry Hogan (R) released his tax returns Friday, a month after his campaign kickoff. He is pictured here during the kickoff at the Union Jack's British Pub in Annapolis. (Pete Marovich for The Washington Post)

Maryland Gov. Larry Hogan (R) released three years’ of tax returns Friday, heading off a potential line of attack from his Democratic challenger, Ben Jealous, who released his returns last month.

In his 2017 return, Hogan listed $760,989 in capital gains, real estate profits and other income in addition to his $178,043 salary as governor. He and his wife reported incomes of $578,571 and $899,432 for 2016 and 2015, respectively.

The release of tax returns became an issue ahead of the June primary as Democrats sought to distinguish themselves from President Trump, who sidestepped tradition by refusing to make his filings public during his 2016 campaign.

State Sen. Richard S. Madaleno Jr. released six years of returns in April and began criticizing other gubernatorial candidates who hadn’t released returns. One after another, most of the candidates running to challenge Hogan released theirs.

Hogan, who owns a real estate business, stayed silent on the issue, with his aides repeatedly declining to say whether he would release his tax returns. One of the front-runners vying to challenge him, Prince George’s County Executive Rushern L. Baker III, declined to release his taxes, saying financial disclosures he filed as an elected official provided adequate information.

But Jealous, who ultimately beat Baker for the nomination, released three years of tax returns a week before the primary, along with a summary of his tax filings from earlier years. Had Hogan not then released his, it would have provided Jealous another talking point for one of his main campaign themes: trying to tie Hogan, who is popular in Maryland, to Trump, who isn’t.

Ahead of Hogan’s election in 2014, he declined to release his returns because his opponent, Lt. Gov. Anthony G. Brown, declined to release his. “We would have done it probably simultaneous with his, but since he’s refusing to do so, we’re certainly not going to,” Hogan told the Associated Press then.

On Friday, Hogan’s allies were quick to laud him for doing so this election season.

“Governor Hogan promised to run an open and transparent administration and the voluntary release of his tax returns is just one more example of how he is keeping that promise,” state Senate Minority Whip Steve Hershey ­(R-Upper Shore) said in an emailed statement.

Hogan’s deputy campaign manager, Doug Mayer, said in an email that “The release of the governor’s tax returns, combined with 5 years of state financial disclosures and private trust documents that have been proactively made public, represent a level of transparency and openness that few, if any, sitting governors have ever matched.”

In 2010, candidate and former governor Robert Ehrlich (R) released partial tax returns during his race against Gov. Martin O’Malley (D), who made his tax returns available to reporters a day later.

Hogan’s eponymous real estate firm headquartered in Anne Arundel County specializes in land deals and commercial brokerage. It also dabbles in residential sales and manages developments elsewhere in the state. After becoming governor, he turned over his business’s operations to trustees close to him.

The State Ethics Commission approved a trust agreement that “includes some of the safeguards generally found in blind trusts,” according to a letter from Hogan to the commission’s director in 2016. He did not create a blind trust because he had “continuing interests in active and ongoing businesses which cannot be placed into a blind trust,” the letter said.

Jealous, in his 2017 return, listed nearly $240,000 in income as a partner at Kapor Capital, a California-based venture capital investment firm that focuses on socially conscious businesses. He also earned $192,192 as a visiting professor at Princeton University’s Woodrow Wilson School and $34,115 from speaking engagements.

Fenit Nirappil contributed to this report.