Adrian Newey has raised concerns that Red Bull's push for this year's titles has compromised their 2014 package.
While some rivals switch development to their 2014 car months ago, Red Bull continued to develop this year's RB9.
Those efforts paid off when Sebastian Vettel's victory at the Indian GP wrapped up both the Drivers' and Constructors' Championships.
However, those titles could yet cost the team next season.
"I guess in terms of development this year, we felt we were being pushed quite hard by our rivals," the Red Bull tech chief told ESPN.
"Ferrari [pushed us] very much at the start [of the season] - Fernando can never be forgotten - and then Mercedes started to look very strong in the mid season.
"We had to keep pushing and we put a lot of work into developing this year's car, which in truth meant some compromise to the development of next year's car, but we felt we needed to do that.
"You could argue with 20:20 hindsight that we could have backed off earlier than we did and put more of our resources into next year, but if we'd done that too early and not got the Championship we'd be feeling pretty sick at the moment."
He added: "Some of what we have learnt will transfer to next year as well because the underlying aerodynamics are still similar.
"Other bits, unfortunately, have met their natural evolution and can't be applied to next year's regulations."
Asked whether Red Bull would be on the limit getting their new car out in time for the first pre-season test in Jerez, Newey said: "Yes, it's a big effort now from everyone to get the car ready for the first test."