CWB: Planning on Monthly Salaries and Budgeting on Annual Salaries?

Hello - we are starting a new CWB implementation in our Latin America region for multiple countries.  Each country stores salaries in monthly amounts but have a different salary basis (12, 13, 13.33, etc.)

The Comp & Ben group in the region are requiring monthly salaries to be shown on the worksheet and allocations to be made in terms of monthly salaries.  In addition, they communicate monthly salary increases to employees.   However, the budget needs to reflect annual salary increases amounts and total allocations made against annual salaries.

Does anyone have experience doing this?  If so are there design decisions we need to take into consideration and do you have any advice?