declare @t table (row_id int,	id int, reserved_kg int,	kg int)
insert into @t values
(1,	570013,	1300,	1869),
(2,	570013,	385,	null),	
(3,	570013,	296,	null),	
(4,	570013,	119,	null),	
(1,	554444,	3300,	2869),
(2,	554444,	385,	null),	
(3,	554444,	296,	null),	
(4,	554444,	119,	null)	

;WITH [CTE]
AS
(
    SELECT row_id, id, reserved_kg, kg
          ,FIRST_VALUE(kg) OVER(PARTITION BY id ORDER BY row_id) - SUM(reserved_kg) OVER(PARTITION BY id ORDER BY row_id ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS remainder
      FROM @t
)
SELECT row_id, id, reserved_kg, kg
      ,CASE
           WHEN remainder < 0
           THEN CASE
                    WHEN remainder + reserved_kg < 0
                    THEN NULL
                    ELSE remainder + reserved_kg
                END
           ELSE reserved_kg
       END AS result
  FROM [CTE]

SUM(reserved_kg) OVER(PARTITION BY id ORDER BY row_id ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)