Both the AUCSA and all its committees delegate approximately 10% of their overall expenses to their unforeseen costs. This is a reserved amount of money that is meant to be used in extreme unforeseen and unpredictable circumstances, and you should always consult with the AUCSA before wanting to use these unforeseen costs. Please note that they are meant for emergencies, such as when rented equipment goes missing or breaks. They are not meant to be an extra buffer to use when you realize one of your events is going to turn out more expensive than you initially planned for, in which case you should always send a preliminary budget proposal to the AUCSA requesting more money or a reallocation of your budget.
The bottom line is: if you need more budget for an event, do not use your unforeseen, but request more budget by emailing a preliminary budget proposal with written justification to your CAO. Additionally, always consult the AUCSA first if you are unsure whether an unexpected cost falls under unforeseen.