First of all, you have to explain what you mean by a variable pay structure. Compensation or remuneration consists of fixed pay or allowances and variable allowances.
For example:
Basic salary is the permanent price of the job, which cannot be reduced because of its market price.
Fixed Allowances: HRA, Transportation, Education, Medical.
Variable Allowances: Shift, Hazardous, Overtime Allowances, Incentives, Commission, Bonus, etc.
Thank you.