The government is acting too slowly and must "face up to some hard choices" about where to allocate cash and staff in the run up to Brexit.
A damning report published today by Public Accounts Committee warns that some departments have already been forced to stop work on some projects in order to "make room" for work on Brexit - but there is still not enough resource being deployed into the matter.
"It is critical that the civil service has the right people, skills and resources to manage exiting the EU. Yet allocation processes have been too slow; the Department for Exiting the European Union (DExEU) and the Cabinet Office do not have a robust enough plan to identify and recruit the people and skills needed quickly. DExEU must pick up the pace of this work and move other departments on to getting things done," the report said.
The influential committee calls for DexEU, Treasury and the Cabinet Office to offer greater transparency and formally set out who is responsible for what, and where progress is being made. The government should also be open about the costs involved.
Deputy chair Geoffrey Clifton-Brown said: "It is one thing to identify the amount of work required to deliver Brexit. It is quite another to do it.
"The government has identified over 300 work streams to complete as a consequence of the UK’s departure from the EU—a byzantinely complicated task with the potential to become a damaging and unmanageable muddle.
"The committee has called for these work streams to be published by April, with a timeline of actions, so that Parliament is able to keep track of the government’s progress in its preparedness to leave the EU.
"It is concerning that government departments still have so far to go to put their plans into practice. DexEU and the Cabinet Office accept the pace of work must accelerate, a point underlined by DexEU’s senior civil servant when he told us that there needs to be a ‘sharp focus on the world of the real’."
He added: "That real world will not wait for the government to get its house in order. There is much at stake and we expect our committee, Parliament and the public to be kept meaningfully informed on what progress is being made, and at what cost."