You can't reference a derived column like that. You can either reuse the logic for Negamt in BLAmt or use a derived table: -- Reuse logicSELECT Project.ProjectCode AS PC, Project.StatusCode AS SC, Time.StandardHours AS Hours, Time.StandardChargeAmt AS StdAmt, Time.TaskUID as UID, Time.StandardChargeRate as Rate, ChargeableFlag, 'Bill' = Case When TaskRule.ChargeableFlag = 0 Then 'Non-Bill' When TaskRule.ChargeableFlag = 1 Then 'Billable' End , --This statement replaces null values in NegotiatedChargeAmt with values from StandardChargeAmt --and creates a new column Negamt Negamt = isnull(nullif(Time.NegotiatedChargeAmt, 0), Time.StandardChargeAmt), 'BLAmt' = Case When TaskRule.ChargeableFlag = 1 Then isnull(nullif(Time.NegotiatedChargeAmt, 0), Time.StandardChargeAmt) End ...-- Or Derived TableSELECT * -- REplace with column names ,Case When ChargeableFlag = 1 Then Negamt EndFROM ( SELECT Project.ProjectCode AS PC, Project.StatusCode AS SC, Time.StandardHours AS Hours, Time.StandardChargeAmt AS StdAmt, Time.TaskUID as UID, Time.StandardChargeRate as Rate, ChargeableFlag, 'Bill' = Case When TaskRule.ChargeableFlag = 0 Then 'Non-Bill' When TaskRule.ChargeableFlag = 1 Then 'Billable' End , --This statement replaces null values in NegotiatedChargeAmt with values from StandardChargeAmt --and creates a new column Negamt Negamt = isnull(nullif(Time.NegotiatedChargeAmt, 0), Time.StandardChargeAmt), ChargeableFlag ... ) AS T