The dividing of a loss proportionately among two or more insurers that cover the same loss.

"Apportionment" In Context

"DERBY— The Board of Apportionment and Taxation this week approved a proposed city budget of $37.2 million for fiscal 2012-2013, which represents a 1.6 million increase over the current spending plan. The mill rate is projected to increase 3.5 ..."