diff --git a/hwe/compare/fixtures/monthly_process_war_income.json b/hwe/compare/fixtures/monthly_process_war_income.json
new file mode 100644
index 00000000..835b9776
--- /dev/null
+++ b/hwe/compare/fixtures/monthly_process_war_income.json
@@ -0,0 +1,96 @@
+{
+  "action": "ProcessWarIncome",
+  "environment": {
+    "year": 193,
+    "month": 1,
+    "startyear": 190
+  },
+  "setup": {
+    "resetCities": true,
+    "nation": [
+      {
+        "id": 1,
+        "values": {
+          "name": "전쟁수입국",
+          "gold": 1000,
+          "level": 1,
+          "type": "che_중립"
+        }
+      },
+      {
+        "id": 2,
+        "values": {
+          "name": "비활성국",
+          "gold": 2000,
+          "level": 0,
+          "type": "che_중립"
+        }
+      },
+      {
+        "id": 3,
+        "values": {
+          "name": "법가국",
+          "gold": 3000,
+          "level": 1,
+          "type": "che_법가"
+        }
+      }
+    ],
+    "city": [
+      {
+        "id": 1,
+        "values": {
+          "nation": 1,
+          "supply": 1,
+          "pop": 1000,
+          "pop_max": 2000,
+          "dead": 101
+        }
+      },
+      {
+        "id": 2,
+        "values": {
+          "nation": 1,
+          "supply": 0,
+          "pop": 1000,
+          "pop_max": 2000,
+          "dead": 999
+        }
+      },
+      {
+        "id": 3,
+        "values": {
+          "nation": 2,
+          "supply": 1,
+          "pop": 1000,
+          "pop_max": 2000,
+          "dead": 1000
+        }
+      },
+      {
+        "id": 4,
+        "values": {
+          "nation": 3,
+          "supply": 1,
+          "pop": 1000,
+          "pop_max": 2000,
+          "dead": 105
+        }
+      },
+      {
+        "id": 5,
+        "values": {
+          "nation": 0,
+          "supply": 1,
+          "pop": 999,
+          "pop_max": 1000,
+          "dead": 10
+        }
+      }
+    ]
+  },
+  "observe": {
+    "cityIds": [1, 2, 3, 4, 5],
+    "nationIds": [1, 2, 3]
+  }
+}
diff --git a/hwe/compare/monthly_event_trace.php b/hwe/compare/monthly_event_trace.php
index 934aae33..69412e70 100644
--- a/hwe/compare/monthly_event_trace.php
+++ b/hwe/compare/monthly_event_trace.php
@@ -179,7 +179,13 @@ function comparisonMonthlyEventTraceMain(): void
             throw new \InvalidArgumentException('request must be an object');
         }
         $actionName = $request['action'] ?? null;
-        if (!in_array($actionName, ['UpdateCitySupply', 'UpdateNationLevel', 'ProcessSemiAnnual'], true)) {
+        $supportedActions = [
+            'UpdateCitySupply',
+            'UpdateNationLevel',
+            'ProcessSemiAnnual',
+            'ProcessWarIncome',
+        ];
+        if (!in_array($actionName, $supportedActions, true)) {
             throw new \InvalidArgumentException('unsupported monthly action');
         }
         $setup = $request['setup'] ?? [];