This study aims to explore whether the insurance company has advantageous information in underwriting renewal business in the information sharing system of the auto insurance market in Taiwan. Results show no significant difference in the profit of insurance companies between underwriting renewal and reinsurance businesses, indicating that the existing information sharing system can provide sufficient information. In addition, the underwriting experience and the agreed supplementary articles for drivers have a positive influence on the profitability of insurance companies. However, this positive influence has no interference effect. Moreover, among the female sample group aged 30–59 with the most incomplete risk classification, profitability from the agreed supplementary articles for drivers is not higher than that of all other samples.