you are using invalid sintax. Try:

CREATE TABLE #Company(companyIDintNOT NULL IDENTITY(1,1)

,recnumintNOT NULL

,nameFormalnvarchar(100)NOT NULL

,parentnvarchar(100)NULL

,recnumParentintNULL

,sourceRefnvarchar(100)NOT NULL

,commentsnvarchar(1000)NULL

,createdBynvarchar(3)NOT NULL

,createdDatedateNOT NULL

,numEmplsintNULL

,emfValidThisCompanychar(1)NOT NULL CHECK (emfValidThisCompany IN('Y', 'N'))

,nameInternal AS LOWER(CASE WHEN nameFormal LIKE 'the %' THEN SUBSTRING(nameFormal,1,LEN(nameFormal)-4) ELSE nameFormal END)

PRIMARY KEY(companyID)

);