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Please select (any or many, all is optional) user or group, start date, project and rate, then press '+' button. Edit/delete rates in table.
Note, Default Rate can be added with empty user field, and non empty rate specified, for all users. Similar for Any Project and empty date (1970-01-01). Zero (0) rate can be added for certain user or project for non-billable work.
Note, rate is determined basing on the following order: user, group, default. So if no rate is defined for user, group rate is looked up, and then default rate.
Caution: if user rate is defined, it is applied, even with empty date and/or project, and no group or default rate is checked, even if it is defined with later date or certain project.
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Please note, if Restricted Groups setting is set in app configuration, current user can only see or set rates for users in groups, the same for the current user and those selected in Restricted Groups. I.e. if jira-developers group is selected in Restricted Groups, and current user is member of that group, then he can see only users that are also members of that group.
Corner case: -1 Hourly Rate in the Cost Report is shown, if Hourly Rates is setup for a group, and current user does not have Browse Users Jira Global Permission.
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Note, Cost Report is available in Timesheet Reports and Gadgets Cloud and Time Reports Server/Cloud., but there is Worklog Clost additional field in Timesheet Reports and Gadgets for Jira Server, see https://www.primetimesheet.net/wiki/Tips_and_Tricks.html#Cost_report_based_on_the_timesheet_information.