The white-collar union, MSF, has teamed up with a pensions administrator, Jacques Martin Unity, to launch the scheme in the spring.
The pensions venture is one of several in which unions are expanding their activities beyond traditional bread-and-butter issues such as wages and conditions. They hope to attract new members and retain their loyalty by offering them extra services.
Usdaw, the shopworkers' union, is setting up a personal pension plan, also administered by Jacques Martin, for its members in the retail trade, many of whom are not covered by employers' schemes.
John Cullen, a manager at Jacques Martin, said that if these two were successful, similar schemes could be set up across other industries, such as road haulage or engineering, where staff tend to work for small employers and receive fewer benefits.
The MSF scheme is aimed at the many thousands of small voluntary organisations, such as charities, that cannot afford to offer staff a guaranteed pension.
Bryan Freake, MSF pensions officer, said the voluntary sector employed about 250,000 people, of which his union represented 30,000. Most worked for large organisations that already had their own occupational pensions. But at least one-third of staff worked for employers with no scheme.
'Essentially, employers would be invited to join by offering them simple benefits on behalf of their staff, such as life cover,' he said. .
'On top of that, the employer and members would be able to make pension contributions, which would go into members' individual pensions accounts. The aim is to protect people. Career mobility in the sector is very high, which can mean working without pension provision.'
Employers and staff members pay in agreed sums of money each year, which are invested. At retirement, the investment is used to buy an annual pension.
'Because it is a money-purchase scheme, it is very flexible. Employers pay in whatever they can afford,' Mr Freake explained.
MSF will not be making money from the arrangement of the scheme; and those taking out a pension do not have to be members of the union.
Mr Cullen said unions did not have to be the only ones to promote such ventures. Trade organiations representing employers within industrial sectors could also do so among their own members if they wished.Reuse content