Abbey Legal Protection has boosted the potential commission on its before-the-event legal assistance policies by five per cent.
The added commission is available to brokers who sell more than five of its commercial legal policies.
Normal commission is 15%.
However, the offer is only planned to last until the end of December 1999.
Lee Gibbons, business development manager at Abbey, said: "We wanted to reward brokers for the support they have given us over the last year and to encourage our new broking relationships to try our system for accessing legal protection for their clients."
Abbey's research shows that only 15% of firms have adequate commercial legal expenses cover.
The insurer said that recent employment law changes, for example raising compensation available at employment tribunals to £50,000 and an unlimited amount in discrimination cases, could drastically affect inadequately insured firms. Abbey's commercial legal expenses policy boasts access to its 24-hour legal advice service.
The insurer believes this is the first in the country to be staffed almost entirely by fully-qualified lawyers.
Abbey, which claims to have 25% of the commercial legal expenses market, has had less success with its after-the-event personal injury cover.
Earlier this month, adverse litigation costs forced the insurer to more then double the premiums for its personal accident conditional fee cover from £155 to £315.