This budget is then used as a guideline for what the Executive Branch thinks they need to do the job. The House creates the appropriations bills, which either reflect the President's wishes or modify it for what they think is needed, based on inputs from the various government agencies. The Senate is then, though they've failed for the past 5 years, supposed to review the House version, suggest changes where they think appropriate. This is where budgets have gone to die.
So, in this case (2015), we have:
1) The WH submitted a proposed budget ( The Budget | The White House
) that recommended $415 billion for Defense (you have to go in and strip the numbers down to operational vs. administrative costs to get to that number). For purposes of discussion, we'll assume that the $495 billion (the overall total) was all operations. (I have no confidence that the WH intended to cut government bureaucrats to get the cost down). Included in that budget were significant cuts to personnel monies - things like cutting commissaries, raising the co-pay on TriCare for veterans, etc. - as well as holding the reimbursement on subsistence and housing allowances (even though the costs of both had gone up), and capping the service pay raise at 1%.
2) The Department of Defense also does a budget exercise which is floated up to the House. In that submission, they asked for what they thought they needed to meet the military mission.
3) The House looked at both proposals and settled on $600 billion for DoD activities. This was based on maintaining the service member benefits, as well as funding important operations and systems.
4) The Senate, once again acting as lap dogs for the President, held to the $495 billion limit. They did this by keeping the service member benefits in place, but cutting the overall size of the military and stopping some new system acquisitions. They were advised by the WH that some of these elements were not needed since we were no longer at war, and, in addition, changed the baseline definition of the mission of the military (a long and convoluted description of which I can provide if you are interested). Suffice it to say, we no longer are as dominant a force as we were three years ago. It was this maneuver that enabled the President to pretend he cut DoD costs, while maintaining our security postures. Those of us in the business would STRONGLY disagree (more on that also, if you wish).
5) In order to get a budget passed, the House acquiesced on the $495 billion limit, recognizing that they had protected the troops. (Clearly, they recognized that stalling the budget - for any reason - was not a politically viable solution.)
Does that answer your question, or did I miss?