College Committees are not VAT registered, therefore are not subject to VAT charged on income, or able to reclaim VAT from expenses.
Organisations that are VAT registered are subject to paying VAT on any income (for example ticket sales). As a College Committee this does not affect you, therefore all money made from ticket sales (minus the booking fee) is kept by your committee.
Organisation that are VAT registered can reclaim VAT on expenses (for example an order of T-Shirts). As College Committees are without VAT registration, this money is unable to be reclaimed by yourselves or York SU.