sweetener
noun [ C ]
uk/ˈswiːtənər/ ussomething that is given to someone in order to make an offer or situation more attractive and acceptable:
a $50m/cash, etc. sweetener The government is to offer a £50m sweetener to persuade workers at state-owned factories facing closure to take new jobs with private companies.
Flexible benefits packages, including extra holiday entitlement, have been offered to employees as a sweetener.