Cost Rate is your internal cost for an employee (e.g., their salary), used to calculate the project's Profit/Loss.
Bill Rate is the rate you charge the client, used to calculate the project's Revenue.
Changing the Cost Rate without changing the Bill Rate will affect the Profit, as Profit = Revenue - Cost.
Troubleshooting
Some users experience problem with the calculations. The issue with the calculation lies in the Cost Rate being applied to the time entry:
When you logged the time entry via time_entries/new, you selected 'me' while logged in as the 'admin' user.
The plugin calculated the cost using the 'admin' user's Cost Rate, not the rate of the user assigned to the task (who has the $10/hour rate).
The 'admin' user likely has a significantly higher Cost Rate configured under Administration → Users → admin → Rates, causing the cost of the 1 hour entry to be much higher than the $10 you expected.
You can check the 'admin' user's rate to verify the exact cost being applied.
Note: Please note that we have made changes to how the Redmine Budgets plugin handles these calculations. We recommend you update to version 1.0.7 (released on 2025-07-15) or above, to ensure accurate budget tracking.