Whyte took over at Ibrox in May and had promised to inject money into the club.
Despite those claims, the Gers could be hit with a £49m tax bill next month, and the businessman is anticipating the need to save money.
"Costs have to be cut going forward," he told STV. "There's no doubt we have got some tough decisions to make.
"We've got a business plan going forward which does involve significant cost savings."
Whyte was the subject of a BBC Scotland documentary on Thursday night which alleged that he had continued to run a company despite being hit with a ban that restricted him from doing so.