SELECT
ROW_NUMBER() OVER(ORDER BY (CONVERT(varchar, effectivedate, 102)) ASC) Rn,
CONVERT(varchar, **effectivedate**, 102) effectivedate,
SUM(EuroCurrentBalance/1000000) TotalArrears,
SUM(CASE WHEN Multiplier > 2 THEN EuroCurrentBalance/1000000 ELSE 0 END) NPLs,
CASE WHEN ROW_NUMBER() OVER(ORDER BY (CONVERT(varchar, effectivedate, 102)) ASC) = 1 THEN 0 ELSE SUM(EuroCurrentBalance/1000000) - (LAG(SUM(EuroCurrentBalance/1000000),1,0) OVER (ORDER BY (CONVERT(varchar, effectivedate, 102)))) END MonthlyChange