The TRIA does not mandate how much insurers should charge for their terrorism cover. The cost of cover is often charged as a fixed percentage of the underlying policies to which it attaches. In practice, this offers a relatively simple mechanism for pricing, but is not without issue. For example, when property premiums rise, due to market ‘hardening’ or claims experience on specific accounts, the cost of TRIA cover will also often increase. This means the amount the policyholder pays for their terrorism cover is not directly related to the risk they present. In contrast, the pricing of standalone terrorism policies is not influenced by property or casualty market conditions or claims history. This ensures clients pay a premium commensurate with their specific exposure, whilst also being protected from unexpected volatility in the rates applied.