Transfers work like this:
When you sell a player, the price stated in the sale can go straight on the books. So we sell a player: £100m, we're £100m up on this years books despite receiving that money over say, 5 years.
When we buy a player, we amortise the purchase, meaning if a player cost us £100m we spread that cost out over the length of his contract, even if we pay everything today. So a 12 year contract would mean it's actually a cost of £8.4m a year on the books.
The end of year dealings would look like this:
Revenue: £100m
Out-goings: £8.4m
Balance: £91.6m
Chelsea are flying dangerously close to the sun here in order to beat FFP, but this in essence my friends is why everyone at Juventus is being banned.