my understanding is we could sign Mata, Witsel and Carvalho for a combined £90m tomorrow (should they want to sign), but we couldn't compensate for the inevitable rise in the wage bill without breaching the FFP regulations, unless we raise our revenue this year. I believe that means the tax year as well (
@The Esk) can clarify, so that could either be by selling a player now or in January.
As I said though, the best way in the long term is through sponsorship to raise revenue and that's what will happen. In the short term though we have to accept that it's likely a major asset will need to be sold.