The deductible expense nature of insurance premiums depends on whether the loss incurred in the absence of insurance is a deductible expense or whether the benefit from the insurance is taxable. If a loss, which is considered as an expense in the absence of insurance, is cove- red by the insurance or if the benefit from the insurance is included in the taxable revenue as a rule, the premium for this insurance should be considered as a deductible expense. Since professional liability insuran- ce includes compensation for the damages arising from the fault of the professional, the expense nature of the premium of this insurance is de- pendent on the expense nature of the compensation arising from the pro- fessional's fault. Although the revenue administration does not accept the compensation payments arising from the fault of the professional as an expense in the determination of the taxable net income, it is seen that they accept the professional liability insurance premiums as an expense. It can be expected that the acceptance of the insurance premium as an expense without complying with the compensations will cause excessive insurance demand and an asymmetric effect on tax revenues. On the ot- her hand, it can be expected that the acceptance of insurance premiums as an expense in line with the compensation will weaken the relationship between fault and make it possible to overcome the limitation that pre- vents the deduction of taxes and penalties from the tax base.