WASHINGTON—A special commission looking for ways to revamp U.S. military benefits is expected to call for the creation of a new 401(k)-type retirement system as part of an overhaul of the existing Pentagon pension plan, an idea certain to face resistance in Washington, according to people briefed on the proposals.

The new retirement plan is one of 15 sweeping recommendations the independent panel is set to unveil Thursday when it releases a 300-page report meant to serve as a road map for President Barack Obama, Congress and...