diff --git a/cl_sii/cte/f29/parse_datos_obj.py b/cl_sii/cte/f29/parse_datos_obj.py
index 3a8a52bf..dde6aa62 100644
--- a/cl_sii/cte/f29/parse_datos_obj.py
+++ b/cl_sii/cte/f29/parse_datos_obj.py
@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+import copy
+import json
 from datetime import datetime
 from decimal import Decimal
 from pathlib import Path
@@ -23,10 +25,17 @@
 )
 CTE_F29_DATOS_OBJ_SCHEMA = read_json_schema(_CTE_F29_DATOS_OBJ_SCHEMA_PATH)
 
+_CTE_F29_DATOS_OBJ_MISSING_KEY_FIXES_PATH = (
+    Path(__file__).parent.parent.parent / 'data' / 'cte' / 'f29_datos_obj_missing_key_fixes.json'
+)
+CTE_F29_DATOS_OBJ_MISSING_KEY_FIXES: SiiCteF29DatosObjType = json.load(
+    open(_CTE_F29_DATOS_OBJ_MISSING_KEY_FIXES_PATH)
+)
+
 
 def parse_sii_cte_f29_datos_obj(
     datos_obj: SiiCteF29DatosObjType,
-    schema_validator: Optional[Callable[[SiiCteF29DatosObjType], None]] = None,
+    schema_validator: Optional[Callable[[SiiCteF29DatosObjType], SiiCteF29DatosObjType]] = None,
     campo_deserializer: Optional[Callable[[object, str], object]] = None,
 ) -> CteForm29:
     """
@@ -55,7 +64,7 @@ def parse_sii_cte_f29_datos_obj(
 
 def _parse_sii_cte_f29_datos_obj_to_dict(
     datos_obj: SiiCteF29DatosObjType,
-    schema_validator: Callable[[SiiCteF29DatosObjType], None],
+    schema_validator: Callable[[SiiCteF29DatosObjType], SiiCteF29DatosObjType],
     campo_deserializer: Callable[[object, str], object],
 ) -> Mapping[str, object]:
     """
@@ -67,17 +76,17 @@ def _parse_sii_cte_f29_datos_obj_to_dict(
     :param campo_deserializer:
     :raises JsonSchemaValidationError: If schema validation fails.
     """
-    schema_validator(datos_obj)
+    validated_datos_obj = schema_validator(datos_obj)
 
     datos_obj_campos: Mapping[int, str] = {
-        int(code): str(value) for code, value in datos_obj['campos'].items()
+        int(code): str(value) for code, value in validated_datos_obj['campos'].items()
     }
-    datos_obj_extras: Mapping[str, object] = datos_obj['extras']
+    datos_obj_extras: Mapping[str, object] = validated_datos_obj['extras']
     datos_obj_glosa: Mapping[int, str] = {  # noqa: F841
-        int(code): str(value) for code, value in datos_obj['glosa'].items()
+        int(code): str(value) for code, value in validated_datos_obj['glosa'].items()
     }
     datos_obj_tipos: Mapping[int, str] = {
-        int(code): str(value) for code, value in datos_obj['tipos'].items()
+        int(code): str(value) for code, value in validated_datos_obj['tipos'].items()
     }
 
     deserialized_datos_obj_campos = {
@@ -156,12 +165,14 @@ def cte_f29_datos_obj_campo_best_effort_deserializer(campo_value: object, tipo:
     return deserialized_value
 
 
-def cte_f29_datos_schema_default_validator(datos_obj: SiiCteF29DatosObjType) -> None:
+def cte_f29_datos_schema_default_validator(
+    datos_obj: SiiCteF29DatosObjType,
+) -> SiiCteF29DatosObjType:
     """
     Validate the ``datos`` object against the schema.
 
     :raises JsonSchemaValidationError: If schema validation fails.
-    :returns: ``None`` if schema validation passed.
+    :returns: Validated ``datos`` object if schema validation passed.
     """
     try:
         jsonschema.validate(datos_obj, schema=CTE_F29_DATOS_OBJ_SCHEMA)
@@ -172,3 +183,82 @@ def cte_f29_datos_schema_default_validator(datos_obj: SiiCteF29DatosObjType) ->
         raise JsonSchemaValidationError("The keys of 'campos' and 'tipos' are not exactly the same")
     if datos_obj['campos'].keys() != datos_obj['glosa'].keys():
         raise JsonSchemaValidationError("The keys of 'campos' and 'tipos' are not exactly the same")
+
+    return datos_obj
+
+
+def cte_f29_datos_schema_best_effort_validator(
+    datos_obj: SiiCteF29DatosObjType,
+) -> SiiCteF29DatosObjType:
+    """
+    Validate the ``datos`` object against the schema.
+
+    If there are missing keys in the `tipos` or `glosa` dicts, it will try to get them
+    from a list of default values.
+
+    :raises JsonSchemaValidationError: If schema validation fails.
+    :returns: Validated ``datos`` object if schema validation passed.
+    """
+    try:
+        validated_datos_obj = cte_f29_datos_schema_default_validator(datos_obj)
+    except JsonSchemaValidationError as exc:
+        if exc.__cause__ is jsonschema.exceptions.ValidationError:
+            # We will not try to fix this kind of error.
+            raise
+        elif exc.__cause__ is None:
+            # Let's try to fix this.
+            new_datos_obj = try_fix_cte_f29_datos(datos_obj)
+
+            # Let's try again.
+            cte_f29_datos_schema_default_validator(new_datos_obj)
+            return new_datos_obj
+        else:
+            raise
+    else:
+        return validated_datos_obj
+
+
+def try_fix_cte_f29_datos(datos_obj: SiiCteF29DatosObjType) -> SiiCteF29DatosObjType:
+    """
+    Try to fix the ``datos`` object.
+
+    If there are missing keys in the `tipos` or `glosa` dicts, it will try to get them
+    from a list of default values.
+
+    :raises JsonSchemaValidationError: If an unfixable issue is found.
+    :returns: A possibly fixed ``datos`` object.
+    """
+    new_datos_obj: Mapping[str, MutableMapping[str, object]]
+    new_datos_obj = copy.deepcopy(datos_obj)  # type: ignore[arg-type]
+
+    campos_tipos_keys_diff = datos_obj['campos'].keys() - datos_obj['tipos'].keys()
+    remaining_campos_tipos_diff = (
+        campos_tipos_keys_diff - CTE_F29_DATOS_OBJ_MISSING_KEY_FIXES['tipos'].keys()
+    )
+    if remaining_campos_tipos_diff:
+        raise JsonSchemaValidationError(
+            "The keys of 'campos' and 'tipos' differ for the following codes: "
+            f"{remaining_campos_tipos_diff}"
+        )
+    else:
+        for missing_key in campos_tipos_keys_diff:
+            new_datos_obj['tipos'][missing_key] = CTE_F29_DATOS_OBJ_MISSING_KEY_FIXES['tipos'][
+                missing_key
+            ]
+
+    campos_glosa_keys_diff = datos_obj['campos'].keys() - datos_obj['glosa'].keys()
+    remaining_campos_glosa_diff = (
+        campos_glosa_keys_diff - CTE_F29_DATOS_OBJ_MISSING_KEY_FIXES['glosa'].keys()
+    )
+    if remaining_campos_glosa_diff:
+        raise JsonSchemaValidationError(
+            "The keys of 'campos' and 'glosa' differ for the following codes: "
+            f"{remaining_campos_glosa_diff}"
+        )
+    else:
+        for missing_key in campos_glosa_keys_diff:
+            new_datos_obj['glosa'][missing_key] = CTE_F29_DATOS_OBJ_MISSING_KEY_FIXES['glosa'][
+                missing_key
+            ]
+
+    return new_datos_obj
diff --git a/cl_sii/data/cte/f29_datos_obj_missing_key_fixes.json b/cl_sii/data/cte/f29_datos_obj_missing_key_fixes.json
new file mode 100644
index 00000000..41fd122d
--- /dev/null
+++ b/cl_sii/data/cte/f29_datos_obj_missing_key_fixes.json
@@ -0,0 +1,8 @@
+{
+  "glosa": {
+    "049": "(Desconocido)"
+  },
+  "tipos": {
+    "049": "M"
+  }
+}
diff --git a/tests/test_cte_f29_parse_datos_obj.py b/tests/test_cte_f29_parse_datos_obj.py
index a567ebe2..8e34bd86 100644
--- a/tests/test_cte_f29_parse_datos_obj.py
+++ b/tests/test_cte_f29_parse_datos_obj.py
@@ -216,3 +216,110 @@ def test_full_2(self) -> None:
             "fecha_presentacion": datetime.date(2019, 1, 22),
         }
         self.assertEqual(dict(obj), expected_dict)
+
+    def test_full_3_file_with_missing_value(self) -> None:
+        datos_obj: Mapping[str, Any] = read_test_file_json_dict(
+            'test_data/sii-cte/f29/cte--61002000-3--f29-6600000016-datos-obj-fake-missing-code-49.json',  # noqa: E501
+        )
+        obj = parse_datos_obj.parse_sii_cte_f29_datos_obj(
+            datos_obj=datos_obj,
+            schema_validator=parse_datos_obj.cte_f29_datos_schema_best_effort_validator,
+        )
+
+        self.assertIsInstance(obj, data_models.CteForm29)
+        self.assertEqual(obj.contribuyente_rut, Rut('61002000-3'))
+        self.assertEqual(obj.periodo_tributario, PeriodoTributario(year=2017, month=7))
+        self.assertEqual(obj.folio, 6600000016)
+
+        expected_codes_dict = {
+            1: "SERVICIO DE REGISTRO CIVIL E IDENTIFICACION",
+            3: Rut('61002000-3'),
+            6: "HUERFANOS 1570",
+            7: 6600000016,
+            8: "SANTIAGO",
+            15: PeriodoTributario(year=2017, month=7),
+            30: 723122062,
+            48: 1409603,
+            49: 211345,
+            60: 70,
+            89: 0,
+            77: 11429763,
+            91: 1536269,
+            92: 0,
+            93: 224400,
+            94: 1603589,
+            151: 126666,
+            315: datetime.date(2017, 8, 28),
+            502: 6588397,
+            503: 9,
+            504: 17037344,
+            511: 980816,
+            519: 30,
+            520: 1481178,
+            527: 2,
+            528: 512805,
+            537: 18018160,
+            538: 6588397,
+            547: 1536269,
+            562: 17296416,
+            584: 10,
+            595: 1536269,
+            761: 1,
+            762: 12443,
+            795: 157080,
+            915: datetime.date(2017, 10, 31),
+            922: "013-2015",
+        }
+        self.assertEqual(obj.as_codes_dict(include_none=False), expected_codes_dict)
+
+        expected_dict = {
+            "contribuyente_rut": Rut('61002000-3'),
+            "periodo_tributario": PeriodoTributario(year=2017, month=7),
+            "folio": 6600000016,
+            "apellido_paterno_o_razon_social": "SERVICIO DE REGISTRO CIVIL E IDENTIFICACION",
+            "apellido_materno": None,
+            "nombres": None,
+            "calle_direccion": "HUERFANOS 1570",
+            "numero_direccion": None,
+            "comuna_direccion": "SANTIAGO",
+            "telefono": None,
+            "correo_electronico": None,
+            "representante_legal_rut": None,
+            "extra": {
+                30: 723122062,
+                48: 1409603,
+                49: 211345,
+                77: 11429763,
+                89: 0,
+                92: 0,
+                93: 224400,
+                151: 126666,
+                502: 6588397,
+                503: 9,
+                504: 17037344,
+                511: 980816,
+                519: 30,
+                520: 1481178,
+                527: 2,
+                528: 512805,
+                537: 18018160,
+                538: 6588397,
+                547: 1536269,
+                562: 17296416,
+                584: 10,
+                595: 1536269,
+                761: 1,
+                762: 12443,
+                795: 157080,
+            },
+            "total_a_pagar_en_plazo_legal": 1536269,
+            "total_a_pagar_con_recargo": 1603589,
+            "pct_condonacion": 70,
+            "num_res_condonacion": "013-2015",
+            "fecha_condonacion": datetime.date(2017, 10, 31),
+            "tipo_declaracion": "Primitiva",
+            "banco": "Banco del Patito Amarillo",
+            "medio_pago": "PEL",
+            "fecha_presentacion": datetime.date(2017, 8, 28),
+        }
+        self.assertEqual(dict(obj), expected_dict)
diff --git a/tests/test_data/sii-cte/f29/cte--61002000-3--f29-6600000016-datos-obj-fake-missing-code-49.json b/tests/test_data/sii-cte/f29/cte--61002000-3--f29-6600000016-datos-obj-fake-missing-code-49.json
new file mode 100644
index 00000000..238c32d8
--- /dev/null
+++ b/tests/test_data/sii-cte/f29/cte--61002000-3--f29-6600000016-datos-obj-fake-missing-code-49.json
@@ -0,0 +1,221 @@
+{
+    "campos": {
+      "001": "SERVICIO DE REGISTRO CIVIL E IDENTIFICACION",
+      "003": "61002000-3",
+      "006": "HUERFANOS 1570",
+      "007": "6600000016",
+      "008": "SANTIAGO",
+      "015": "201707",
+      "030": "723122062",
+      "048": "1409603",
+      "049": "211345",
+      "060": "70",
+      "077": "11429763",
+      "089": "0",
+      "091": "1536269",
+      "092": "0",
+      "093": "224400",
+      "094": "1603589",
+      "151": "126666",
+      "315": "28/08/2017",
+      "502": "6588397",
+      "503": "9",
+      "504": "17037344",
+      "511": "980816",
+      "519": "30",
+      "520": "1481178",
+      "527": "2",
+      "528": "512805",
+      "537": "18018160",
+      "538": "6588397",
+      "547": "1536269",
+      "562": "17296416",
+      "584": "10",
+      "595": "1536269",
+      "761": "1",
+      "762": "12443",
+      "795": "157080",
+      "915": "31/10/2017",
+      "922": "013-2015"
+    },
+    "extras": {
+      "ADM8703": "",
+      "ADM8721": "",
+      "BANCO": "Banco del Patito Amarillo",
+      "CALIDADDECLARANTE": "Contribuyente",
+      "CARTRIB": "1",
+      "CLASE": "Primitiva",
+      "CODINT": "580000019",
+      "COD_FORM": "F29",
+      "DV_ORIGEN": "3",
+      "FECHA_HOY": "16/10/2019",
+      "FECHA_INGRESO": "28082017",
+      "FOLIO": "6600000016",
+      "MEDIO_INGRESO": "INTERNET",
+      "MEDIO_PAGO": "PEL",
+      "MOSTRAR_FOLIO": "1",
+      "NOMBRES": " SERVICIO DE REGISTRO CIVIL E IDENTIFICACION ",
+      "NOMBRE_FUN": "  ",
+      "OPCION": "VC",
+      "PERIODO": "201707",
+      "RUT_ORIGEN": "61002000",
+      "TIPO_MOVIMIENTO": "1",
+      "TOKEN": "VFC",
+      "USUARIO": "0",
+      "cant_anuladas": 0
+    },
+    "folioF": {},
+    "glosa": {
+      "001": "APELLIDO PATERNO O RAZ\u00d3N SOCIAL",
+      "003": "N DE RUT",
+      "006": "DIRECCION",
+      "007": "FOLIO",
+      "008": "COMUNA",
+      "015": "PERIODO TRIBUTARIO",
+      "030": "PPM ART. 84, A) PERD. ART. 90",
+      "048": "RET. IMP. \u00daNICO TRAB. ART. 74 N 1 LIR",
+      "060": "PORCENTAJE CONDONACION TGR",
+      "077": "REMANENTE DE CR\u00c9DITO FISC.",
+      "089": "IMP. DETERM. IVA DETERM.",
+      "091": "TOTAL A PAGAR DENTRO DEL PLAZO",
+      "092": "REAJUSTES",
+      "093": "Intereses y multas",
+      "094": "Total a pagar con recargo",
+      "151": "RET, TASAS DE 10 % SOBRE LAS RENT.  ",
+      "315": "FECHA TIMBRE CAJA",
+      "502": "D\u00c9BITOS FACTURAS EMITIDAS",
+      "503": "CANTIDAD FACTURAS EMITIDAS",
+      "504": "REMANENTE CREDITO MES ANTERIOR",
+      "511": "CR\u00c9D. IVA POR DCTOS. ELECTRONICOS",
+      "519": "CANT. DE DCTOS. FACT. RECIB. DEL GIRO",
+      "520": "CR\u00c9DITO REC. Y REINT./FACT. DEL GIRO",
+      "527": "CANT. NOTAS DE CR\u00c9DITO RECIBIDAS",
+      "528": "CR\u00c9DITO RECUP. Y REINT NOTAS DE CR\u00c9D",
+      "537": "TOTAL CR\u00c9DITOS",
+      "538": "TOTAL D\u00c9BITOS",
+      "547": "TOTAL DETERMINADO",
+      "562": "MONTO SIN DER. A CRED. FISCAL",
+      "584": "CANT.INT.EX.NO GRAV.SIN DER. CRED.FISCAL",
+      "595": "SUB TOTAL IMP. DETERMINADO ANVERSO",
+      "761": "CANT. FACT. SUPERMERCADOS Y SIMILARES",
+      "762": "CR\u00c9D. FACT. SUPERMERCADOS Y SIMILARES",
+      "795": "MONTO DE CONDONACION SII",
+      "915": "Fecha de Vigencia de Condonacion",
+      "922": "NUMERO RESOLUCION SII AUTO. CONDONACION"
+    },
+    "justif": {
+      "001": "I",
+      "003": "I",
+      "006": "I",
+      "007": "I",
+      "008": "I",
+      "015": "I",
+      "030": "I",
+      "048": "I",
+      "060": "I",
+      "077": "I",
+      "089": "D",
+      "091": "-",
+      "092": "-",
+      "093": "-",
+      "094": "-",
+      "151": "I",
+      "315": "I",
+      "502": "D",
+      "503": "I",
+      "504": "D",
+      "511": "I",
+      "519": "I",
+      "520": "D",
+      "527": "I",
+      "528": "D",
+      "537": "D",
+      "538": "D",
+      "547": "D",
+      "562": "D",
+      "584": "I",
+      "595": "D",
+      "761": "I",
+      "762": "D",
+      "795": "I",
+      "915": "-",
+      "922": "-"
+    },
+    "linea": {
+      "001": "0",
+      "003": "0",
+      "006": "0",
+      "007": "0",
+      "008": "0",
+      "015": "0",
+      "030": "56",
+      "048": "49",
+      "049": "0",
+      "060": "0",
+      "077": "47",
+      "089": "47",
+      "091": "119",
+      "092": "120",
+      "093": "121",
+      "094": "122",
+      "151": "50",
+      "315": "0",
+      "502": "7",
+      "503": "7",
+      "504": "33",
+      "511": "23",
+      "519": "27",
+      "520": "27",
+      "527": "29",
+      "528": "29",
+      "537": "46",
+      "538": "22",
+      "547": "104",
+      "562": "26",
+      "584": "26",
+      "595": "74",
+      "761": "27",
+      "762": "27",
+      "795": "0",
+      "915": "0",
+      "922": "0"
+    },
+    "tipos": {
+      "001": "C",
+      "003": "R",
+      "006": "C",
+      "007": "N",
+      "008": "C",
+      "015": "N",
+      "030": "M",
+      "048": "M",
+      "060": "N",
+      "077": "M",
+      "089": "M",
+      "091": "M",
+      "092": "M",
+      "093": "M",
+      "094": "M",
+      "151": "M",
+      "315": "F",
+      "502": "M",
+      "503": "N",
+      "504": "M",
+      "511": "M",
+      "519": "N",
+      "520": "M",
+      "527": "N",
+      "528": "M",
+      "537": "M",
+      "538": "M",
+      "547": "M",
+      "562": "M",
+      "584": "N",
+      "595": "M",
+      "761": "N",
+      "762": "M",
+      "795": "M",
+      "915": "F",
+      "922": "C"
+    }
+  }