You may need to delimit the grouping based on the new account determination procedure effective date. You can hard code the date or use a constant in V_T511K, with a value zero for the earlier period and value 1 from the effective date.
This type of effective date is used in both time eval & payroll schema/PCR's. In payroll, you can use CMPER operation - where you can delimit based on for-period or in-period. For-period is a common type of delimiting.