The Elizabeth line was due to start taking passengers this December.
But the opening through central London has now been pushed back to “autumn 2019”.
The Enquirer first reported about Crosssrail’s problems during the crucial fit out phase more than two years ago.
Project chiefs repeated the mantra constantly that the job was “on time and on budget”.
It is now £590m over budget and nine months late.
Crossrail said: “Crossrail Limited has been working hard to maintain the programme and sufficient testing time is required to introduce the next phase of the railway – the central section between Paddington and Abbey Wood – in a way that can be guaranteed to be safe and reliable.
“The original programme for testing has been compressed by more time being needed by contractors to complete fit-out activity in the central tunnels and the development of railway systems software.
“Testing has started but further time is required to complete the full range of integrated tests.”
Simon Wright, Crossrail Chief Executive said: “We have made huge progress with the delivery of this incredible project but we need further time to complete the testing of the new railway.
“We are working around the clock with our supply chain and Transport for London to complete and commission the Elizabeth line.”
Crossrail chiefs pocketed more than £800,000 in bonus payments last year.
The bonus figures were contained in Transport for London’s draft annual report for the financial year to March 31 2018.
They relate to bonuses earned in 2016/17 and paid in 2017/18.
The report details pay for the 20 Crossrail executives employed that year who had a base salary of more than £150,000
The biggest beneficiary was former chief executive Andrew Wolstenholme who left the project in March.
Wolstenholme was paid a performance related bonus of £160,000 on top of his base salary of £476,772.
He was also paid “compensation for loss of employment” of £97,734.
Wolstenholme left in March to take up a new role as as group managing director at the Maritime and Land division of BAE Systems.
Programme Director Simon Wright – who took over Wolstenholme’s role – was given a £105,568 bonus on top of his base salary of £328,873.