Red Hat, the Triangle software company, has been promised more than a year in free rent and huge discounts afterwards as part of a sweet deal from Progress Energy to lease a vacant office building in downtown Raleigh.

Red Hat said this week in a federal regulatory filing it expects to receive at least $28 million from Progress toward its real estate rent.

The terms of the real estate lease effectively mean that Red Hat will be paid by Progress, a Fortune 500 electric utility, to occupy the building for more than five years of the lease.

Officials at Progress and Red Hat could not be reached for comment to elaborate on their real estate contract. However, Progress has been under pressure to find a tenant to occupy the headquarters it plans to dismantle as part of its corporate merger with Charlotte-based Duke Energy.

Red Hat had initially expected to begin moving in at 100 E. Davie Street this month, but the move has been delayed by several months. According to Red Hat's filing Tuesday with the Securities and Exchange Commission, Progress will have to make the building available for Red Hat by Jan. 1, 2013.

Progress and Duke had expected to have their $26 billion deal completed by the end of this year but glitches with federal regulators mean the merger will likely take three to six more months to complete, setting back Red Hat's move from N.C. State University's Centennial Campus to downtown Raleigh.

Progress is freeing up one of its two downtown office towers because the company is eliminating between 700 and 1,000 jobs in Raleigh, a part of a broader plan by Progress and Duke to eliminate 1,860 jobs over three years.

According to Red Hat's SEC filing, its monthly base rent will be $380,000 from July 1, 2013 through Dec. 31, 2020.

But Red Hat won't make full payments every year. Progress will provide an "initial improvement allowance" on July 1, 2012 in the amount of $3.2 million, a year before Red Hat is scheduled to start paying rent. For the following three years, Progress will credit Red Hat's rent to the tune of $3.2 million each year -- or $12.8 million over four years -- offsetting much of the software maker's annual $4.6 million rent bill.

Red Hat's rent will go down to $320,000 a month -- or $3.8 million a year -- starting in 2021. The lease will expire Aug. 23, 2035.

But for four of those years -- from 2028 through 2031 -- Progress will provide "additional improvement allowance" to Red Hat. The allowance will be a credit equal to the amount of Red Hat's base rent, or a total of $15.2 million.