Mitsui Mutual Life Insurance Co. will completely outsource its back-office duties related to insurance in April, sources familiar with the plan said Sunday.

Mitsui Mutual will pay 36 billion yen to IBM Japan Ltd. to take care of its clerical operations for 10 years through an equally owned joint venture, the sources said.

The move is aimed at cutting costs and upgrading services.

Mitsui Mutual will convert itself from a mutual entity to a joint-stock company in April.

The joint venture, NBC Customer Service, will have initial capital of 10 million yen and will be in charge of receiving insurance premiums. It will be headed by a Mitsui Mutual executive.

The venture will also be tasked with providing costumer services and handling other clerical operations.

Mitsui Mutual will remain in charge of core insurance operations, such as decisions about policy underwriting and developing new products, the sources said.

The insurer will eventually transfer 1,000 employees, or more than 20 percent of its workforce of 4,700, to the venture. IBM Japan will send 30 personnel, including a vice president and engineers.