WITH cl AS
(select o.LINEID, o.BILL, o.[Total Amount],
(select SUM([Total Amount]) from bills t where o.BILL = t.BILL and o.LINEID >= t.LINEID) as 'sum_total_ammount'
from bills o inner join payment p on o.BILL = p.BILL)
select o.LINEID, o.BILL, o.[Total Amount],
case when p.[Paid Amount] >= sum_total_ammount then o.[Total Amount]
else (o.[Total Amount] - sum_total_ammount + p.[Paid Amount]) end as 'Allocated Amount'
from cl o inner join payment p on o.BILL = p.BILL
and (o.[Total Amount] - sum_total_ammount + p.[Paid Amount]) > 0
Ecco una demo su SqlFiddle .
