diff --git a/docs/work-items/ET-005/04-test-plan.yaml b/docs/work-items/ET-005/04-test-plan.yaml
new file mode 100644
index 0000000..1c85195
--- /dev/null
+++ b/docs/work-items/ET-005/04-test-plan.yaml
@@ -0,0 +1,33 @@
+name: ET-005 Unit Toggle Test Plan
+tests:
+  - id: TP-01
+    title: Default unit is km
+    steps:
+      - Clear localStorage
+      - Load page
+    expected: All distances shown in km
+
+  - id: TP-02
+    title: Toggle to miles
+    steps:
+      - Click km/mi button
+    expected: All distances recalculated to miles
+
+  - id: TP-03
+    title: Persistence
+    steps:
+      - Switch to miles
+      - Reload page
+    expected: Miles still selected after reload
+
+  - id: TP-04
+    title: Toggle back to km
+    steps:
+      - While in miles mode, click button
+    expected: Distances back in km
+
+  - id: TP-05
+    title: Mobile responsive
+    steps:
+      - Open on 375px viewport
+    expected: Button visible and clickable
\ No newline at end of file