diff --git a/tests/assets/users_csvimport_bugs_1811.csv b/tests/assets/users_csvimport_bugs_1811.csv
new file mode 100644
index 00000000..13f50258
--- /dev/null
+++ b/tests/assets/users_csvimport_bugs_1811.csv
@@ -0,0 +1,2 @@
+UserMixedCase_1811_A@example.com, ,"Mixed Case LDAP User 1811A",Viewer,none,no,mixedcase_1811_a@example.com,TableauID
+UserMixedCase_1811_B@example.com, ,"MFA User 1811B",Creator,none,no,mfa_1811_b@example.com,TableauIDWithMFA
diff --git a/tests/e2e/online_tests.py b/tests/e2e/online_tests.py
index 8f1d50d6..4c38d1fc 100644
--- a/tests/e2e/online_tests.py
+++ b/tests/e2e/online_tests.py
@@ -74,6 +74,7 @@ def get_publishable_name(file_value: str) -> str:
     TWB_FILE_WITH_EMBEDDED_CONNECTION = "EmbeddedCredentials.twb"
 
     USERS_DETAILS_FILE = "detailed_users.csv"
+    USERS_CSVIMPORT_1811_FILE = "users_csvimport_bugs_1811.csv"
     USERNAMES_FILE = "usernames.csv"
 
 
@@ -316,6 +317,41 @@ def test_users_create_site_users(self):
         arguments = [command, users, "--role", "Publisher"]
         _test_command(arguments)
 
+    @pytest.mark.order(2)
+    def test_users_create_site_users_csvimport_bugs_1811(self):
+        """Round-trip coverage for five of the six ``UserItem.CSVImport`` bugs
+        fixed in tableau/server-client-python#1811 (issue #1809). Once tabcmd
+        delegates its CSV stack to TSC's ``CSVImport``, this fixture is the
+        regression guarantee that the delegation preserved each fix.
+
+        Exercises, in one two-row CSV:
+
+        * the 8-column AUTH bound (row length now readable),
+        * mixed-case usernames preserved verbatim (case-sensitive auth systems),
+        * ``TableauIDWithMFA`` accepted in the auth allowlist,
+        * capitalised role/admin/publisher tokens accepted case-insensitively,
+        * the ``@property_is_enum(Auth)`` guard active on the parsed
+          ``UserItem.auth_setting``.
+
+        The sixth bug (unknown-AUTH rejection) is a negative-path check that
+        doesn't fit a single happy-path fixture; TSC's own unit tests cover it.
+
+        ``--no-complete`` skips tabcmd's duplicate strict validator so the CSV
+        actually reaches TSC's ``UserItem.CSVImport`` — which is what this test
+        is meant to exercise. No ``--role`` override, so the role field in each
+        row is what gets validated (that's the point of the case-insensitivity
+        check).
+
+        Related: tabcmd #297 (license-name case sensitivity), #434 (``Local``
+        auth accepted by the CLI but rejected server-side).
+        """
+        if not server_admin and not site_admin:
+            pytest.skip("Must be server or site administrator to create site users")
+        command = "createsiteusers"
+        users = os.path.join("tests", "assets", TestAssets.USERS_CSVIMPORT_1811_FILE)
+        arguments = [command, users, "--no-complete"]
+        _test_command(arguments)
+
     @pytest.mark.order(3)
     def test_group_creategroup(self):
         if not server_admin and not site_admin: