West Ham are currently competing for a top four place and Champions League football.
The Hammers are expected to be busy in the summer as they look to build on an impressive first season under the Croatian.
A striker is thought to be top of their wish list, with the club having been linked to a number of top forwards across Europe already.
Much will rest on the money they have to spend as the type of man they need is not likely to come cheaply.
And Bilic admits that finance, who they can sell and whether they are in Europe will determine their transfer policy.
“We are all working hard on plans for next season,” he told the London Evening Standard.
“We will do some business but how much we don’t know yet. It depends on the financial situation; on who goes and — to a lesser extent — on whether we are in Europe.”
If being in Europe is a factor for West Ham’s transfer policy, they will be hoping that they can secure a top four place this season.
The Hammers are currently sixth in the table and six points behind Manchester City, who occupy fourth spot and that last Champions League place.
Crucially though, they have a game in hand, against 5th placed Manchester United, and win over them would open up the race for the top four.