The Teessiders, who seem certain to spend a fifth successive season in the Championship, will look to reduce their expenditure on salaries from around £16million to £10million as they attempt to comply with the Financial Fair Play rules.
Mowbray told the Northern Echo: "It all comes down to finance. You have only got so much to spend.
"There will be some players leaving this summer, whether they are loan players or out of contract, and we will save a certain amount of money on their salaries.
"That will take us to ground zero if you like, the level where we are committed to paying so much over the year for the players that remain. But if that number is still greater than where you want to get to in terms of wages, you are in a bit of trouble.
"If you talk about recruitment and bringing players in, someone else might have to go to get to a position where you can start spending a bit of money."