diff --git a/src/planecli/commands/projects.py b/src/planecli/commands/projects.py
index e0fddda..83f335a 100644
--- a/src/planecli/commands/projects.py
+++ b/src/planecli/commands/projects.py
@@ -36,6 +36,11 @@
 }
 
 
+def _default_identifier(name: str) -> str:
+    """Derive a default project identifier from the project name."""
+    return "".join(c for c in name if c.isalnum())[:5].upper()
+
+
 def _enrich_project(data: dict) -> dict:
     """Add convenience fields to a project dict."""
     network = data.get("network")
@@ -157,9 +162,8 @@ async def create(
         client = get_client()
         workspace = get_workspace()
 
-        create_data = CreateProject(name=name)
-        if identifier:
-            create_data.identifier = identifier.upper()
+        resolved_identifier = (identifier or _default_identifier(name)).upper()
+        create_data = CreateProject(name=name, identifier=resolved_identifier)
         if description:
             create_data.description = description
 
diff --git a/tests/test_projects.py b/tests/test_projects.py
new file mode 100644
index 0000000..bbca584
--- /dev/null
+++ b/tests/test_projects.py
@@ -0,0 +1,19 @@
+"""Tests for the project commands module."""
+
+from __future__ import annotations
+
+from planecli.commands.projects import _default_identifier
+
+
+class TestDefaultIdentifier:
+    def test_derives_from_name(self):
+        assert _default_identifier("Frontend App") == "FRONT"
+
+    def test_strips_punctuation(self):
+        assert _default_identifier("My Backend API!") == "MYBAC"
+
+    def test_keeps_short_name(self):
+        assert _default_identifier("FE") == "FE"
+
+    def test_uppercases(self):
+        assert _default_identifier("backend") == "BACKE"