The figure is part of its planned £2.4bn "efficiency savings" announced earlier this year. TfL said its 10-year business plan would "de-layer management, eliminate duplication, reduce headcount and improve technology".
The company said it wouldmake the £400m worth of savings though "IT improvements". The areas it will tackle include desktop services, datacentre and hosting services, application portfolio management and voice and data network services.
It is also hoping the new Oyster contracts will deliver savings.
A spokesman for the company said, "The changes are focused on support and non-operational functions including, among many other areas, our IT activities, so that we continue to improve our passenger services while we deliver this massive investment programme. Around IT, TfL will be consolidating its budgets and delivering £400m in savings over the plan period."
The company also plans to reduce its headcount, but said "much of the reduction" would be achieved by not filling vacancies and transferring employees into roles currently filled by temporary staff.