The station projects are being delivered for Network Rail by Hochtief, Graham and VolkerFitzpatrick.
In a monthly update to the London Assembly, Crossrail chief Mark Wild revealed all station completions had now been pushed into next year.
He said that despite recent progress at Romford, West Drayton, Ealing Broadway and Hayes & Harlington, the pandemic site lockdown had impacted the programme.
“As a result of the temporary pause of Network Rail works due to Covid-19, it is likely that these enhanced stations, along with llford, Southall, Acton Main Line and West Ealing, will be completed as soon as possible in 2021.
He added: “Network Rail are also working hard to complete the power supply upgrade on the Great Eastern Route.
“This involves reinforcing power supplies between Liverpool Street and Gidea Park.
“Final work is due to take place from November through to January with the system commissioned by April 2021.
“Completing the outstanding works and commencing intensive operational testing in early 2021 remain our top priorities.”