National Mutual is cutting its branch network to 11 offices from the current 18.
The move is likely to cost 25 backroom staff their jobs as the pensions specialist cuts its staff from 100 to 75.
Its 90-strong broker sales force remains unaffected.
National Mutual blames the cutbacks on the continuing market pressure to drive down costs and charges. This has led to slashed margins as pension providers aim to keep there market share.
The seven offices to be closed are Belfast, Chelmsford, Croydon, Leicester, Sheffield, Southampton and Newcastle. Their sales support functions will be transferred in the summer.