A review of the military pay system to be started this year will likely not be completed before early 2019, Pentagon officials said.

That timeframe, they said, is typical for the congressionally mandated study, known as the Quadrennial Review of Military Compensation, or QRMC. To start the review, the Defense Department traditionally requests the review order from the president, who then sets the study in motion.

The regularly scheduled review will be done instead of a separate, additional study ordered by Congress last year on whether or not the Defense Department can move from the current military pay structure to a salary system, according to a letter sent by Pentagon officials to lawmakers in April.

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"A transition to a salary system would be a change of historic proportions, and significant additional study is necessary to understand the second and third order effects, the potential risks to readiness, if any, and the effects of the DoD's ability to recruit and retain the nation's all-volunteer force," the letter, sent to the House and Senate armed services committees and signed by senior defense executive A.M. Kurta said. "The additional study required to fully analyze, understand and anticipate future effects from this type of change has necessarily and most appropriately been performed by the Quadrennial Review of Military Compensation."

The last stand-alone QRMC was published in June of 2012. The regularly scheduled 2016 study order was shelved by President Barack Obama after Congress in 2013 ordered the Military Compensation and Retirement Modernization Commission, or MCRMC.

The MCRMC report made a series of military benefits recommendations, including a plan to revamp the military retirement system and one to plus-up troop financial education. Versions of both of those were included by Congress in the 2016 National Defense Authorization Act through a new retirement program known as the Blended Retirement System.

-- Amy Bushatz can be reached at amy.bushatz@military.com.