Lighthouse Group has renewed its contract to provide financial advice to the members of Prospect after a competitive tender.
The deal will see Lighthouse offer its services to the trade union's 142,000 members who are engineers, scientists, managers and specialists in areas as diverse as agriculture, broadcasting, defence, energy, shipbuilding, telecoms and transport.
Malcolm Streatfield, chief executive of Lighthouse, said: "The board is very pleased that we have secured this contract renewal with Prospect, which serves to endorse further the quality of service and financial planning support which Lighthouse Financial Advice provides for all participating members in our affinity relationships.
"We very much look forward to further progressing our relationship with Prospect over the years ahead. The board remains committed to developing further our affinity partnerships throughout the UK."
Lighthouse has a number of partnerships with major employee organisations, including Unison, BA Clubs, the University and College Union and the Royal College of Nursing.
Mike Clancy, general secretary of Prospect, said: "We are very pleased to have secured this contract renewal with Lighthouse, which will enable us to continue to ensure that our members are able to access financial planning assistance from a reliable and well reputed organisation, able to cater for a broad range of financial planning requirements.
"Given the truly national basis of our membership, it is important to us to continue to partner with an organisation which is clearly capable of supporting our members no matter where they may reside and no matter what their background.
"We look forward to continuing to develop our relationship with Lighthouse and ensuring that our members are able to secure quality service and consistent financial advice."