Aviva is to underwrite all individual income protection (IP) policies on an own occupation basis, including part-time occupations.
Around 90 job types will be newly underwritten under own occupation terms as a result of the changes.
The changes will be applied to all new individual IP policies from 21 October 2013, including part-time cases where the customer works fewer than 16 hours a week, a first for the industry.
The own occupation terms will remain throughout the life of the policy and all claims will be paid on this basis for the full duration of the claim.
The majority of these occupations are driving roles, but also include specific teaching professions such as PE teacher and music teacher, as well as postal delivery people.
However, the insurer revealed 68 occupations will be excluded, the majority of which are occupations from the arts.
Craig Colton, protection managing director for Aviva said: "With just one definition for all the occupations we cover, anyone who is incapacitated and cannot do the duties of their occupation can be confident they will have a successful claim - regardless of what they do and how many hours they work.
"By moving to 100% own occupation terms we fully expect to help even more customers if they are unable to work in the future."