This function: fn_Week_Period_Act() was designed based on accounting (payroll) periods that start on a Saturday. This can be applied against a set of records like timesheets or checks. Then this information can be aggregated based on the accounting week (sat - fri) instead of the calendar week (sun - sat). The function is an inline table function with 1 (datetime) parameter. This can be called by itself as:
SELECT CurrentDate, WeekID, StartWeek, EndWeek FROM dbo.fn_Week_Period_Act(CURRENT_TIMESTAMP)
This can also be JOINed or CROSS APPLYed to an existing table as:
SELECT ts.Emp_ID, ts.Name, ts.Work_Date, wpa.WeekID, wpa.StartWeek, wpa.EndWeek FROM dbo.TimeSheets AS ts CROSS APPLY dbo.fn_Week_Period_Act(ut.Work_Date) AS wpa
Have a good day and enjoy.