How to sum up expenditure month wise

you need to create a stored proc for doing this.
before you need to get starting date and end date of the month. from the front end using code.

create proc prcTotal(@ImpId int, @sDate datetime, @eDate datetime)
on tbl_name
as
(
Declare @total int,
Declare @month varchar(20),
Select @total = sum(Expenditure) from tbl_name where date_col=@sDate between Date_col=@eDate
Select EmpId, 'Month'= case
when 'Condition for month' then 'January',
when 'Condition for month' then 'February',
when 'Condition for month' then 'March',
when 'Condition for month' then 'April',
when 'Condition for month' then 'May',
when 'Condition for month' then 'June',
when 'Condition for month' then 'July',
when 'Condition for month' then 'August',
when 'Condition for month' then 'September',
when 'Condition for month' then 'October',
when 'Condition for month' then 'November',
when 'Condition for month' then 'December',
'MonthExpenditure'=@total where EmpId=@EmpId and Date_col=@sDate and Date_col=@eDate
)

try this.

The query should be similar to the following..

SELECT EmpID
       , DATENAME(Month, cast( Date as datetimeoffset)) as  Month
       , sum(Expenditure) as TotalExpenditure
      
FROM Employee
GROUP BY EmpID, DATENAME(Month, cast( Date as datetimeoffset))