diff --git a/resources/tester/test_est_review_workflow.py b/resources/tester/test_est_review_workflow.py
index 39e2cf319..28a021bc9 100644
--- a/resources/tester/test_est_review_workflow.py
+++ b/resources/tester/test_est_review_workflow.py
@@ -80,3 +80,17 @@ def test_review_reset_one_row_keeps_other_inputs():
     )
     assert result["after"]["edits"] == {"row:2": {"GN": 3, "Reason": "second"}}
     assert result["removed"]
+
+
+def test_fixed_review_preserves_amount_for_reason_or_quantity_only():
+    result = run(
+        "math",
+        """(()=>{
+      const p=EstNative.empty();p.tables.EstMainDat=[{PkID:1,Name:'fixed',GN:1,TC:100,CalcIndex:1}];
+      return [{Reason:'checked'},{GN:3},{GC:20}].map(edit=>{
+        p.contractReview={edits:{'row:1':edit}};
+        return EstReview.calculate(p).reviewed.tables.EstMainDat[0].TC;
+      });
+    })()""",
+    )
+    assert result == [100, 100, 20]
diff --git a/tools/est-test/native-review.js b/tools/est-test/native-review.js
index 9a6c26d5a..e3fd711cc 100644
--- a/tools/est-test/native-review.js
+++ b/tools/est-test/native-review.js
@@ -61,7 +61,8 @@ const EstReview = (() => {
           errors.push(`${row.Name || key}: 심사할 수 없는 항목 ${field}`);
         else row[field] = edit[field];
       }
-      if (fixed(row)) row.TC = EstMath.sum(row);
+      if (fixed(row) && EstMath.components.some((field) => Object.hasOwn(edit, field)))
+        row.TC = EstMath.sum(row);
     });
     for (const key of Object.keys(edits))
       if (!seen.has(key)) errors.push(`심사 대상 내역 없음: ${key}`);