The council's cabinet met to discuss the new site in 2005 and estimated costs to be around £580,000, however by 2006 this had already jumped to £2.2M.
Discussions with partner Capita meant around £600,000 had to be added to the estimate making a total of £2.8M.
The project, jointly run by the council and it's technology partner, Service Birmingham (the council's joint venture with Capita) is now due for completion at the end of the month, but there are still some concerns.
Deputy council leader Paul Tilsley, responsible for business transformation, told a scrutiny committee last month that he was wary of switching on the new site.
Cllr Tilsley said he feared journalists would be logging on at 9am on the first morning in an attempt to identify 'glitches'.
The Council says that the website is integral to its business transformation plans, which will save the council £1bn over 10 years.The escalating costs were revealed by a Freedom of Information (FOI) request from campaigning journalist Heather Brooke, of the Your Right To Know website.
