If I may make a fine point:

It is more accurate to say that in a multi-statement batch, the statement (query) preceding a CTE should be terminated by a semi-colon.

I find the following just a little easier to grasp: (Change MonthCount to int)

With CTE_Base (SeqNo, Begin_Date, Month_Count, Payment)

as

(select SeqNo, Date_Field AS Begin_Date,Month_Count, Payment from dbo.abc

UNION all

select SeqNo, dateadd(mm, 1, Begin_Date), Month_Count -1, Payment from CTE_Base

where Month_Count > 1

)

SELECT SeqNo, Begin_Date, Month_Count, Payment

FROM CTE_Base

order by SeqNo, Begin_Date