The staff -- mainly working in functions like human resources, marketing and communication -- will have their bonuses shifted from a variable scheme to a fixed percentage of their salary.
The move aimed to reduce uncertainty around compensation rather than to scale back the amount paid, the bank said.
"While not guaranteed, variable compensation is anticipated to be around one-half of a month's salary. In a good performance year for the group, variable compensation can be higher," UBS said in a statement.
UBS said the new process, which would apply to bonuses paid this year, would "streamline" the process of calculating payments.
(Reporting by John Revill; Editing by Michael Shields)