"We calculate it will be about a $14 billion delta in that given year than what we had planned," Work said at a Defense One conference. "That's going to be a harder target to hit, and we're working through that right now."
Conversely, Work said, "If '16 had been a big, big delta in what we had been planning that would have been extremely, extremely disruptive. We're happy to say it's within reach. So we don't expect '16 to be a huge, major disruption."
The good news, as Work sees it, is stability.
"The big thing is we no longer have to worry about fighting for '16 and worrying about '17," Work said.
Under the budget plan, fiscal 2016 defense spending would be raised to $607 billion, $5 billion less than the top-line figure that authorizers budgeted before the deal.
Work added that because he does not expect the budget deal to be signed before Dec. 11, it effectively means the funding for FY16 really only covers nine months, rather than a full fiscal year.
Work later said that details of the so-called "Third Offset" technology development push, a signature effort for both Work and Secretary of Defense Ash Carter, will become more clear when the FY 2017 budget request drops in February.
Joe Gould contributed to this report.
Aaron Mehta was deputy editor and senior Pentagon correspondent for Defense News, covering policy, strategy and acquisition at the highest levels of the Defense Department and its international partners.