Northern Rock is looking to cut its workforce by 680 by the end of 2011.
It claims compulsory redundancies will be avoided where possible.
The state-owned bank has entered formal consultation with Unite, the union, and other employee representatives, on further restructuring of the business.
It says it entered 2011 with a high retained cost base, and needs to reduce this if it is to return to the private sector.
Ron Sandler, executive chairman, said: &’147″Economic and trading conditions remain very challenging for a bank like Northern Rock the mortgage market remains subdued