diff --git a/CHANGELOG.md b/CHANGELOG.md
index e7947b0b..dac1acda 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,10 @@
 
 - **Python 3.10 is no longer supported, and Python 3.15 is.** Python 3.10 reached end of life in October 2026; `requires-python` is now `>=3.11`. Python 3.15 is now tested in CI and listed as supported.
 
+### Bug fixes
+
+- **Unknown child elements under an aggregate record's `<identifiers>` and inside a `<reason>` are no longer copied into the parsed report** ([#948](https://github.com/domainaware/parsedmarc/issues/948)). `_parse_report_record()` copied both mappings whole, so an element that RFC 9990 Appendix A and RFC 7489 Appendix C do not define reached the JSON, Kafka, S3 and webhook outputs with whatever structure the report gave it. Only `header_from`, `envelope_from` and `envelope_to`, and a reason's `type` and `comment`, are kept. **Compatibility:** a consumer of those outputs that read such an extra key no longer receives it.
+
 ## 11.2.2
 
 ### Security
diff --git a/parsedmarc/__init__.py b/parsedmarc/__init__.py
index 894213dd..50dc41cc 100644
--- a/parsedmarc/__init__.py
+++ b/parsedmarc/__init__.py
@@ -829,14 +829,16 @@ def _parse_report_record(
             reasons = policy_evaluated["reason"]
         else:
             reasons = [policy_evaluated["reason"]]
+    normalized_reasons = []
     for reason in reasons:
         # `comment` and `type` are strings in both schemas, but a sender can
         # give them child elements (a dict) or repeat them (a list), and the
         # CSV writer joins them as strings (GHSA-4272-4r8g-6c5h). They follow
         # the rule of every other string field: see _scalar().
-        reason["comment"] = _scalar(reason.get("comment"))
-        reason["type"] = _scalar(reason.get("type"))
-        reason_type = reason["type"]
+        reason_type = _scalar(reason.get("type"))
+        normalized_reasons.append(
+            {"type": reason_type, "comment": _scalar(reason.get("comment"))}
+        )
         if is_rfc_9990 and reason_type in RFC_7489_REMOVED_POLICY_OVERRIDE_TYPES:
             logger.warning(
                 "Policy override reason type %r was removed in RFC 9990; "
@@ -855,15 +857,16 @@ def _parse_report_record(
                 reason_type,
                 sorted(RFC_9990_POLICY_OVERRIDE_TYPES),
             )
-    new_policy_evaluated["policy_override_reasons"] = reasons
+    new_policy_evaluated["policy_override_reasons"] = normalized_reasons
     new_record["policy_evaluated"] = new_policy_evaluated
-    if "identities" in record:
-        new_record["identifiers"] = record["identities"].copy()
-    else:
-        new_record["identifiers"] = record["identifiers"].copy()
-    _scalar_fields(
-        new_record["identifiers"], ("header_from", "envelope_from", "envelope_to")
+    raw_identifiers = (
+        record["identities"] if "identities" in record else record["identifiers"]
     )
+    new_record["identifiers"] = {
+        key: _scalar(value)
+        for key, value in raw_identifiers.items()
+        if key in ("header_from", "envelope_from", "envelope_to")
+    }
     new_record["auth_results"] = {"dkim": [], "spf": []}
     if type(new_record["identifiers"]["header_from"]) is str:
         lowered_from = new_record["identifiers"]["header_from"].lower()
diff --git a/tests/test_init.py b/tests/test_init.py
index 09499bb9..afce0af9 100644
--- a/tests/test_init.py
+++ b/tests/test_init.py
@@ -1309,6 +1309,45 @@ class Test(unittest.TestCase):
                 record, config=parsedmarc.ParserConfig(offline=True)
             )
 
+    def testAggregateRecordProjectsSchemaFields(self):
+        """Unknown identifier and override-reason children stay out of the output.
+
+        RFC 9990 Appendix A and RFC 7489 Appendix C define only header_from,
+        envelope_from and envelope_to under identifiers, and only type and
+        comment in a reason, so unknown children, nested or not, are not
+        copied into the parsed output (#948).
+        """
+        with open(
+            "samples/aggregate/!example.com!1538204542!1538463818.xml",
+            encoding="utf-8",
+        ) as sample:
+            xml = sample.read()
+        xml = xml.replace(
+            "<identifiers>",
+            "<identifiers><foo><x>1</x></foo>"
+            "<envelope_from>bounce.example.com</envelope_from>"
+            "<envelope_to>example.net</envelope_to>",
+            1,
+        ).replace(
+            "</policy_evaluated>",
+            "<reason><type>other</type><comment>test</comment>"
+            "<foo><x>1</x></foo></reason></policy_evaluated>",
+            1,
+        )
+        record = parsedmarc.parse_aggregate_report_xml(xml, offline=True)["records"][0]
+        self.assertEqual(
+            record["identifiers"],
+            {
+                "header_from": "example.com",
+                "envelope_from": "bounce.example.com",
+                "envelope_to": "example.net",
+            },
+        )
+        self.assertEqual(
+            record["policy_evaluated"]["policy_override_reasons"],
+            [{"type": "other", "comment": "test"}],
+        )
+
     def testParseReportRecordMissingDkimSpf(self):
         """Record with missing dkim/spf auth results defaults correctly"""
         record = {
@@ -1382,7 +1421,7 @@ class Test(unittest.TestCase):
         self.assertIsNone(reasons[1]["comment"])
 
     def testParseReportRecordIdentities(self):
-        """'identities' key is mapped to 'identifiers'"""
+        """'identities' key is mapped to 'identifiers'; an unknown key is dropped"""
         record = {
             "row": {
                 "source_ip": "192.0.2.1",
@@ -1396,14 +1435,21 @@ class Test(unittest.TestCase):
             "identities": {
                 "header_from": "Example.COM",
                 "envelope_from": "example.com",
+                "foo": {"x": "1"},
             },
             "auth_results": {"dkim": [], "spf": []},
         }
         result = parsedmarc._parse_report_record(
             record, config=parsedmarc.ParserConfig(offline=True)
         )
-        self.assertIn("identifiers", result)
-        self.assertEqual(result["identifiers"]["header_from"], "example.com")
+        self.assertEqual(
+            result["identifiers"],
+            {
+                "header_from": "example.com",
+                "envelope_from": "example.com",
+                "envelope_to": None,
+            },
+        )
 
     def testParseReportRecordDkimDefaults(self):
         """DKIM result defaults: selector='none', result='none' when missing"""