CFDs are a high-stakes gamble that could lose investors more than they put down.
When asked about whether there would be a contingency plan focused on financial stability in the event of a vote to leave the EU, Charles Roxburgh, director general for financial services at the Treasury, said: "I can give you a simple and clear answer.
"It's the government's policy not to do contingency planning. So we will not be doing contingency planning - that's consistent with the position we had on Scotland, so that's the answer to your question."
In other words - no. The UK Treasury doesn't have a contingency plan because it's not the Treasury's job and the Bank of England will handle it.
Roxburgh said the Treasury support the government's policy to advocate remaining in the European Union until 28 days before the June 23 referendum.
At which point it will "go into purdah" and stop all work relating to the vote.
The job of working out a contingency has fallen instead to the Bank of England.
Governor Mark Carney said this week that, while the Bank won't predict an outcome of the vote, it will come up with plans to deal with the possible market ructions if the UK exits the EU.
The threat of a Brexit has pushed the pound down to below $1.40 this week - lows not seen since the wake of the global financial crisis.