The phrase "extra expense" is used to describe a cost or money that is spent in addition to what was originally planned or budgeted. It refers to any unexpected or additional payments that need to be made. Full definition
Those areas have problems and extra expenses of their own. (biggerpockets.com)
Travel default coverage will prevent such incidents from ruining travel plans by providing compensation for extra expenses incurred in engaging a new travel supplier. (travelinsurancereview.net)
There's no need to worry for extra expenses in order for their virtual assistants to undergo such trainings for the particular skills needed. (accrispin.blogspot.ru)