Within the community currency world the term bonus refers to a premium paid to those who exchange legal tender currency for a community currency. Typically, bonuses take the form of a gift, issued in the community currency, added on top of the amount exchanged.
Bonuses act as incentives to attract new users or to retain existing ones. Malus is the opposite of bonus.
Until December 31st, 2013 the Brixton Pound had a bonus of 10% for those who exchanged their Pound Sterling into the local currency. Although the exchange rate between Brixton Pound and Pound Sterling remains at 1 to 1, the bonus functioned as an encouragement to convert to and use the local currency rather than Pound Sterling.