--- a/ucs-school-umc-exam/umc/python/schoolexam/__init__.py	
+++ a/ucs-school-umc-exam/umc/python/schoolexam/__init__.py	
@@ -51,13 +51,14 @@ 
 from univention.management.console.modules.sanitizers import StringSanitizer, DictSanitizer, ListSanitizer, DNSanitizer
 from univention.management.console.modules.schoolexam import util
 
+from univention.admin.uexceptions import noObject
 from univention.lib.i18n import Translation
 from univention.lib.umc_connection import UMCConnection
 
 from ucsschool.lib.schoolldap import LDAP_Connection, SchoolBaseModule, SchoolSearchBase, SchoolSanitizer
 from ucsschool.lib import internetrules
 from ucsschool.lib.schoollessons import SchoolLessons
-from ucsschool.lib.models import ComputerRoom, ExamStudent, Student, User
+from ucsschool.lib.models import ComputerRoom, ExamStudent, User
 
 _ = Translation('ucs-school-umc-exam').translate
 
@@ -252,32 +253,22 @@ def _thread():
 			percentPerUser = 25.0 / (1 + len(users))
 			examUsers = set()
 			usersReplicated = set()
+			home_directories_to_remove = set()
 			for iuser in users:
 				progress.info('%s, %s (%s)' % (iuser.lastname, iuser.firstname, iuser.username))
-				if iuser.dn.endswith(Student.get_container(request.options['school'])):
-					# its a student. check if home directory from previous
-					# user with same username exists and remove it
-					exam_dn = 'uid={}{},{}'.format(
-						user_prefix_exam,
-						iuser.username,
-						ExamStudent.get_container(request.options['school']))
-					try:
-						ldap_user_read.get(exam_dn, required=True)
-					except ldap.NO_SUCH_OBJECT:
-						_tmp_split_path = iuser.homedir.rsplit(os.path.sep, 1)
-						if len(_tmp_split_path) != 2:
-							MODULE.error("Failed parsing homeDirectory of original user: %s" % (iuser.homedir,))
-						else:
-							exam_user_homedir = os.path.join(_tmp_split_path[0], iuser.username)
-							if os.path.exists(exam_user_homedir):
-								MODULE.warn('Removing stale home directory %r.' % exam_user_homedir)
-								shutil.rmtree(exam_user_homedir, ignore_errors=True)
+				remove_home_directory_prior = False
+				try:
+					ExamStudent.from_student_dn(ldap_user_read, request.options['school'], iuser.dn)
+				except noObject:
+					remove_home_directory_prior = True
 				try:
 					ires = connection.request('schoolexam-master/create-exam-user', dict(
 						school=request.options['school'],
 						userdn=iuser.dn
 					))
 					examUsers.add(ires.get('examuserdn'))
+					if remove_home_directory_prior:
+						home_directories_to_remove.add(ires.get('examuserdn'))
 					MODULE.info('Exam user has been created: %s' % ires.get('examuserdn'))
 				except (HTTPException, SocketError) as exc:
 					MODULE.warn('Could not create exam user account for %r: %s' % (iuser.dn, exc))
@@ -325,6 +316,14 @@ def _thread():
 				MODULE.error('replication timeout - %s user objects missing: %r ' % ((len(examUsers) - len(usersReplicated)), (examUsers - usersReplicated)))
 				raise UMC_Error(_('Replication timeout: could not create all exam users'))
 
+			for userdn in usersReplicated:
+				if userdn in home_directories_to_remove:
+					try:
+						user = ExamStudent.from_dn(userdn, None, ldap_user_read)
+					except noObject:
+						continue
+					shutil.rmtree(user.homedir, ignore_errors=True)
+
 			# update the final list of recipients
 			my.project.recipients = recipients
 			my.project.save()