SQL Summary of Status total values by Month of Type2 SC Dimension

I have a voucher status history table as a type2 slowly changing dimension table I am trying to get the summary total value of each status by each month before a particular date. This is my schema and insert code:

CREATE TABLE #HDimVouchers(
       [HVoucherKey] [bigint] IDENTITY(1,1) NOT NULL,
       [Voucher_id] [bigint] NOT NULL,
       [VoucherStatusKey] [int] NOT NULL,
       [Voucher_amt] [decimal](18, 2) NULL,    
       [DateStatusStart] [date] NULL,       
       [DateStatusEnd] [date] NULL
     
)
--drop table #HDimVouchers
insert #HDimVouchers 
values
(10,2,10.00,'2019-01-01','2019-02-15'),
(10,4,10.00,'2019-02-16',null),
(13,4,10.00,'2019-01-10',null),
(11,2,15.00,'2019-01-01',null),
(12,2,20.00,'2019-03-12','2019-03-12'),
(12,4,20.00,'2019-03-13',null),
(15,2,205.00,'2019-05-25','2020-04-24'),
(15,6,205.00,'2020-04-25',null),
(21,2,100.00,'2019-02-16',null)

I would like to get a summary to total value by year-month by voucherstatuskey something like the below:

[Year-Month]	[VoucherStatusKey]	[Amount]
201901	2	25
201901	4	10
201902	2	100
201902	4	10
201903	4	20
201905	2	205
201906	2	205
201907	2	205
201908	2	205
201909	2	205
201910	2	205
201911	2	205
201912	2	205
202001	2	205
202002	2	205
202003	2	205

I have had many attempts to get the data as above, but I am struggling to get the correct format and values. Below is something I have tried

SELECT  convert(nvarchar(4),Year([DateStatusStart])) + RIGHT('00' + CONVERT(NVARCHAR(2), DATEPART(Month, [DateStatusStart])), 2)
,[VoucherStatusKey]
,SUM([Voucher_amt]) OVER (PARTITION BY Year([DateStatusStart]),Month([DateStatusStart]), [VoucherStatusKey] ORDER BY [DateStatusStart]) AS running_total 
FROM #HDimVouchers where [DateStatusStart] < '2020-03-31';

Solution

Let me assume that you want the value at the end of the month. Then, you can take the following approach:

Generate all appropriate months for each voucher.
Use a join to bring in the appropriate value.

For the first part, you could use a tally or calendar table if one is available. However a recursive CTE is also convenient:

with vdates as (
      select voucher_id, eomonth(min(DateStatusStart)) as eom
      from HDimVouchers
      group by voucher_id
      union all
      select voucher_id, eomonth(dateadd(month, 1, eom))
      from vdates
      where eom < '2020-03-01'
     )
select vd.*, hv.Voucher_amt
from vdates vd join
     HDimVouchers hv
     on hv.voucher_id = vd.voucher_id and
        vd.eom >= hv.DateStatusStart and
        (vd.eom <= hv.DateStatusEnd or hv.DateStatusEnd is null)
order by vd.eom, vd.voucher_id;

Here is a db<>fiddle.