Markey announced last week he would release his returns in the near future and said they would go as far back as Gomez’s disclosure. Gomez, on Wednesday, released six years of returns.

Gomez’s campaign has tried to paint Markey as a Washington insider. In releasing his returns Wednesday, Gomez urgEd MarkeyEdward (Ed) John MarkeyNet neutrality supporters predict tough court battle over FCC's repeal plan Avalanche of Democratic senators say Franken should resign Driverless car bill hits Senate speed bump MORE to do the same.

“Despite being paid by the taxpayers for the last 37 years, he still has yet to release a single year of tax returns. Gabriel Gomez has released his, what’s Congressman Ed Markey hiding?” his campaign told the Globe.

Gomez’s work at a private equity firm proved to be the biggest source of profit. He took home $3 million in 2007 for his work at Advent International.

The Globe noted that Gomez did not release returns going back to 2005, the year in which he claimed a nearly $300,000 tax deduction on his home, which has historical significance. The tax deductions has spurred attacks in the state.

During the primary, Gomez released a five-year overview of his returns that claimed he paid a 20 percent tax rate and brought in $8.5 million.