Divide and conquer with three queries

QueryA:
SELECT UserID, BranchId
FROM Employees, Branches

QueryB:
SELECT UserID, BranchID
FROM Employees

QueryC:
SELECT QueryA.UserID, QueryA.BranchID
FROM QueryA LEFT JOIN QueryB
ON QueryA.UserID = QueryB.UserID AND
      QueryA.BranchID = QueryB.BranchID
WHERE QueryB.UserID is Null and QueryB.BranchID is Null

You can try to do this all in one query as follows
SELECT QueryA.UserID, QueryA.BranchID
FROM (
  SELECT UserID, BranchId
   FROM Employees, Branches
             ) as QueryA
LEFT JOIN (
  SELECT UserID, BranchID
  FROM Employees
                   ) as QueryB
ON QueryA.UserID = QueryB.UserID AND
      QueryA.BranchID = QueryB.BranchID
WHERE QueryB.UserID is Null and QueryB.BranchID is Null