This represents the percentage of a company’s net premiums written that went toward underwriting expenses, such as commissions to agents and brokers, state and municipal taxes, salaries, employee benefits and other operating costs. The ratio is computed by dividing underwriting expenses by net premiums written. The ratio is computed by dividing underwriting expenses by net premiums written. A company with an underwriting expense ratio of 31.3% is spending more than 31 cents of every dollar of net premiums written to pay underwriting costs. It should be noted that different lines of business have intrinsically differing expense ratios. For example, boiler and machinery insurance, which requires a corps of skilled inspectors, is a high expense ratio line. On the other hand, expense ratios are usually low on group health insurance.