The Royal Bank of Scotland International (RBSI) said it is cutting 90 jobs at its offshore centres, which include Jersey, Guernsey, the Isle of Man and Gibraltar.
The bank has not yet said how many jobs will go at each centre.
The number of staff working for RSBI in Jersey is 900, in the Isle of Man it is 580, Gibraltar 180 and Guernsey 180.
The bank said it hoped jobs could be cut "naturally" as staff retire or opt for voluntary redundancy.
Ian Henderson, RBSI chief executive, said: "We understand that any reduction in the number of jobs is regrettable and we will support our staff through this difficult time.
"Our aim is to achieve this through natural staff turnover and voluntary redundancy.
"However, in light of more challenging market conditions, it is essential to create a structure that reflects changing customer requirements as well as the need to achieve cost efficiencies.