BBC head of news James Harding has told staff that he expecting to have to cut £80m a year from the department's budget by 2021.
This is almost equivalent to axing radio station 5Live (budget £49.1m a year) and the BBC News Channel (budget £46.2m a year).
Harding said in a blog post: "BBC News must contribute its share to achieve the £150 million of annual savings required to reach the shortfall to 2017 caused by the decline in TV household penetration.
"BBC News is committed to £5 million as part of this effort. As I said last year, we are also looking to make savings in how we run BBC Online; I will lay these out when I present the findings of the Online Creative Review…
"And by the spring we have to present a plan of how we propose to meet BBC News’ share of the £550 million annual savings required by 2021/22."
Harding said he will draw up plans for the savings over the next three months.
A BBC spokesman said: "No decisions have been taken and no recommendations have yet been made about the Future of BBC News. This is an internal project and this morning we shared with staff the ideas and input so far, before we work through the detail of our proposals.”
As of October 2015, BBC News had 7,355 staff.