select a.name, bi.id_bill, t.price --, t.[sum] 
from bill as b
inner join account as a on b.id_account = a.id
OUTER APPLY (
    SELECT
        sum(bi.price) AS price
        --, sum(p.sum) AS [sum]
    FROM bill_item as bi
    left join payment as p on p.bill_id = bi.id_bill
    WHERE bi.id_bill = b.id
) AS t
WHERE b.month = {{Month}}
and b.year = {{Year}}
order by a.name;

select a.name, t.id_bill, t.price --, t.[sum] 
from bill as b
inner join account as a on b.id_account = a.id
inner join (
    SELECT
        bi.id_bill AS id,
        sum(bi.price) AS price
        --, sum(p.sum) AS [sum]
    FROM bill_item as bi
    left join payment as p on p.bill_id = bi.id_bill
    GROUP BY bi.id_bill
) AS t ON t.id = b.id
WHERE b.month = {{Month}}
and b.year = {{Year}}
order by a.name;