In our company, vacation accrual occurs according to years of service. The definition of the Benefit Accrual Plan includes the months of service and the amount to be accrued. When you define the Benefit Accrual Plan you must also provide the Payroll Frequency in which the accrual will occur. Lets assume that the accrual is as follows:
From 0 month of service to 47.99 months of service the vacation accrual is 8 hours
After 48 months of service the vacation accrual is 10 hours

Here is the situation we have right now:
We have biweekly payroll. The current configuration indicates that the vacation accrual will occur on the second biweekly payroll. For the month of May the payroll dates are 5/14/2021 and 5/28/2021. Since second payroll of the month is 5/28/2021, this is where the accrual process will take place. Let also assume that we have an employee with a seniority date of 5/25/2017. The accrual for this employee has been 8 hours but on 5/25/2021 his months of service will be 48 months so he should accrue 10 hours for the month of May. The payroll date 5/28/2021 covers the period 5/9/2021 to 05/22/2021.

Now, because the Period end date is 5/22/2021 and the accrual is linked to the payroll process (there is no separate option for the accrual process), the employee will not get the correct accrual in May, instead of 10 hours he gets 8 hours. In June he will get the 10 hours accrued.

My suggestion is that the accrual process should not be linked to the payroll process. For example, in Microsoft GP the accrual process is not linked to the payroll process. There is a separate process where you run the accrual and enter the accrual date. When you use the last day of the month for this process you make sure that every employee accrues the correct amount.

Thanks.