The government plans to use ¥1.5 trillion in the pension special account that has been untapped for a quarter of a century to partially finance the payment of public pension benefits, sources said.

The government has opened the way for using the reserve with its pension system reform plan, although the plan will hardly offer a solution to the fiscal crisis in the nation's pension system, as public pension payments now exceed ¥50 trillion a year.

The reserve is a pool of premiums contributed between fiscal 1961 and 1985 by full-time housewives of salaried employees, including civil servants, who voluntarily joined the national pension plan. Consisting of premiums totaling ¥724.6 billion and interest on them, the reserve has grown to ¥1.53 trillion.

With the Diet passing a bill earlier this month to merge the employee pension program for company workers and the mutual aid pension program for civil servants as part of integrated tax and social security reforms, the government is expected to start using the reserve after the law is put into force in October 2015, the sources said.

Full-time housewives of salaried workers have not been required to contribute premiums to the national pension plan since April 1986. The use of reserves voluntarily paid by them between fiscal 1961 and 1985 has been frozen due to the shortage of data on their husbands' affiliation with the employee pension and mutual aid pension programs.