Seventeen players, including Itoje, have been given fixed agreements that will earn them Stg 160,000 ($A315,000) per year as part of a new arrangement between the Rugby Football Union and Premiership clubs.
It also allows head coach Steve Borthwick to have the final say on all sports science and medical matters related to those players.
Those not on enhanced Elite Player Squad contracts will receive a match fee of Stg 23,000 ($A45,000) which hinges on their selection, creating a two-tier system within Borthwick's squad as they gear up for the visit of New Zealand on Saturday and the Wallabies the following week.
Ben Spencer, Will Stuart and Chandler Cunningham-South are three starters in Saturday's autumn opener at Twickenham not in possession of a contract, and there are seven players in the same position on the bench.
Itoje, however, insists England's core group know their agreements will not be renewed if they under-perform, while the availability of up to eight more contracts provide an incentive for others to deliver on the pitch.
"Steve has set the tone. He said whether you have one of these or not, his job is to pick the best 23 or 15 to represent England and to do the job on Saturday (against New Zealand)," the Saracens captain said.
"The aspiration will be to get a contract, but these things are changing. Just because you have a set of players for one season doesn't mean that they are going to be there for the next season and the season beyond. These things are fluid.
"Steve has made everyone aware that if you are an enhanced player and not performing then you won't play and you won't have one for very long.
"All of us have to make sure there is no divide, but I don't foresee that being a real bone of contention."
Itoje will on Saturday surpass the total of 84 caps held by World Cup-winning captain Martin Johnson, who was also a world-class second row.
