This is a Sage HRMS question. (is there another group I should add this type to?).
As companies accrue PTO in HRMS, the financial liability is also accrued. But that liability is a function of the hours and the CURRENT pay rate. So when and employee gets a raise, his/her account needs another bump.
We don't see a function in HRMS/Payroll to do this more or less as part of normal processing. What are we missing?