diff --git a/src/aki_prj23_transparenzregister/utils/data_extraction/unternehmensregister/transform/common.py b/src/aki_prj23_transparenzregister/utils/data_extraction/unternehmensregister/transform/common.py
index 25f54b1..6d30ad6 100644
--- a/src/aki_prj23_transparenzregister/utils/data_extraction/unternehmensregister/transform/common.py
+++ b/src/aki_prj23_transparenzregister/utils/data_extraction/unternehmensregister/transform/common.py
@@ -1 +1,123 @@
 """Common functions for data transformation."""
+import re
+import typing
+from collections.abc import Sequence
+
+from aki_prj23_transparenzregister.models.company import (
+    CompanyRelationshipEnum,
+    CompanyToCompanyRelationship,
+    Location,
+    RelationshipRoleEnum,
+)
+from aki_prj23_transparenzregister.utils.string_tools import (
+    transform_date_to_iso,
+)
+
+
+def traversal(data: dict, path: Sequence[str | int | object]) -> typing.Any:
+    """Traverse a dict using list of keys.
+
+    Args:
+        data (dict): Data export
+        path (Sequence[str  |  int  |   object]): List of keys
+
+    Raises:
+        KeyError: If key not found
+
+    Returns:
+        any: Value at the end of the path
+    """
+    current = data
+    for key in path:
+        try:
+            current = current[key]
+        except KeyError as e:
+            raise KeyError(f"Key {key} not found") from e
+    return current
+
+
+def normalize_street(street: str) -> str:
+    """Normalize street names by extending them to `Straße` or `straße`.
+
+    Args:
+        street (str): Name of street
+
+    Returns:
+        str: Normalized street name
+    """
+    if street is None:
+        return None
+    regex = r"(Str\.|Strasse)"
+    street = re.sub(regex, "Straße", street)
+    regex = r"(str\.|strasse)"
+    street = re.sub(regex, "straße", street)
+    return street.strip()
+
+
+def extract_date_from_string(value: str) -> str | None:
+    """Extract a date in ISO format from the given string if possible.
+
+    Args:
+        value (str): Input text
+
+    Returns:
+        str | None: Date in ISO format, None if not found
+    """
+    date_regex = [  # type: ignore
+        {"regex": r"\d{1,2}\.\d{1,2}\.\d{4}", "mapper": transform_date_to_iso},
+        {"regex": r"\d{4}-\d{1,2}-\d{1,2}", "mapper": None},
+    ]
+    results = []
+    for regex in date_regex:
+        result = re.findall(regex["regex"], value)  # type: ignore
+        if len(result) == 1:
+            relevant_data = result[0]
+            if regex["mapper"] is not None:  # type: ignore
+                results.append(regex["mapper"](relevant_data))  # type: ignore
+            else:
+                results.append(relevant_data)
+    if len(results) != 1:
+        return None
+    return results[0]
+
+
+def map_co_relation(data: dict) -> dict:
+    """Search for and map the c/o relation from location.street if possible.
+
+    Args:
+        data (dict): Company dict
+
+    Returns:
+        dict: Modified Company dict
+    """
+    street = data["location"].street
+    if street is None:
+        return data
+    parts = street.split(",")
+    co_company = None
+    co_company_index = None
+    for index, part in enumerate(parts):
+        trimmed_part = part.strip()
+        result = re.findall(r"^c\/o(.*)$", trimmed_part)
+        if len(result) == 1:
+            co_company = result[0].strip()
+            co_company_index = index
+    if co_company_index is not None:
+        del parts[co_company_index]
+        street = "".join(parts).strip()
+        data["location"].street = street
+
+        if co_company is not None and co_company != "":
+            relation = CompanyToCompanyRelationship(
+                RelationshipRoleEnum.CARE_OF,  # type: ignore
+                Location(
+                    data["location"].city,
+                    street,
+                    data["location"].house_number,
+                    data["location"].zip_code,
+                ),
+                CompanyRelationshipEnum.COMPANY,  # type: ignore
+                co_company,
+            )
+            data["relationships"].append(relation)
+    return data
diff --git a/src/aki_prj23_transparenzregister/utils/data_extraction/unternehmensregister/transform/v1/v1.py b/src/aki_prj23_transparenzregister/utils/data_extraction/unternehmensregister/transform/v1/v1.py
index d9e8868..834b1e5 100644
--- a/src/aki_prj23_transparenzregister/utils/data_extraction/unternehmensregister/transform/v1/v1.py
+++ b/src/aki_prj23_transparenzregister/utils/data_extraction/unternehmensregister/transform/v1/v1.py
@@ -17,6 +17,11 @@ from aki_prj23_transparenzregister.models.company import (
     PersonToCompanyRelationship,
     RelationshipRoleEnum,
 )
+from aki_prj23_transparenzregister.utils.data_extraction.unternehmensregister.transform.common import (
+    extract_date_from_string,
+    map_co_relation,
+    normalize_street,
+)
 from aki_prj23_transparenzregister.utils.string_tools import (
     remove_traling_and_leading_quotes,
     transform_date_to_iso,
@@ -149,24 +154,6 @@ def parse_stakeholder(data: dict) -> CompanyRelationship | None:
     return None
 
 
-def normalize_street(street: str) -> str:
-    """Normalize street names by extending them to `Straße` or `straße`.
-
-    Args:
-        street (str): Name of street
-
-    Returns:
-        str: Normalized street name
-    """
-    if street is None:
-        return None
-    regex = r"(Str\.|Strasse)"
-    street = re.sub(regex, "Straße", street)
-    regex = r"(str\.|strasse)"
-    street = re.sub(regex, "straße", street)
-    return street.strip()
-
-
 def loc_from_beteiligung(data: dict) -> Location:
     """Extract the company location from the first relationship in the export.
 
@@ -338,33 +325,6 @@ def map_business_purpose(data: dict) -> str | None:
         return None
 
 
-def extract_date_from_string(value: str) -> str | None:
-    """Extract a date in ISO format from the given string if possible.
-
-    Args:
-        value (str): Input text
-
-    Returns:
-        str | None: Date in ISO format, None if not found
-    """
-    date_regex = [  # type: ignore
-        {"regex": r"\d{1,2}\.\d{1,2}\.\d{4}", "mapper": transform_date_to_iso},
-        {"regex": r"\d{4}-\d{1,2}-\d{1,2}", "mapper": None},
-    ]
-    results = []
-    for regex in date_regex:
-        result = re.findall(regex["regex"], value)  # type: ignore
-        if len(result) == 1:
-            relevant_data = result[0]
-            if regex["mapper"] is not None:  # type: ignore
-                results.append(regex["mapper"](relevant_data))  # type: ignore
-            else:
-                results.append(relevant_data)
-    if len(results) != 1:
-        return None
-    return results[0]
-
-
 def map_founding_date(data: dict) -> str | None:
     """Extracts the founding date from a given Unternehmensregister export.
 
@@ -457,48 +417,6 @@ def map_last_update(data: dict) -> str:
     return data["XJustiz_Daten"]["Fachdaten_Register"]["Auszug"]["letzte_Eintragung"]
 
 
-def map_co_relation(data: dict) -> dict:
-    """Search for and map the c/o relation from location.street if possible.
-
-    Args:
-        data (dict): Company dict
-
-    Returns:
-        dict: Modified Company dict
-    """
-    street = data["location"].street
-    if street is None:
-        return data
-    parts = street.split(",")
-    co_company = None
-    co_company_index = None
-    for index, part in enumerate(parts):
-        trimmed_part = part.strip()
-        result = re.findall(r"^c\/o(.*)$", trimmed_part)
-        if len(result) == 1:
-            co_company = result[0].strip()
-            co_company_index = index
-    if co_company_index is not None:
-        del parts[co_company_index]
-        street = "".join(parts).strip()
-        data["location"].street = street
-
-        if co_company is not None and co_company != "":
-            relation = CompanyToCompanyRelationship(
-                RelationshipRoleEnum.CARE_OF,  # type: ignore
-                Location(
-                    data["location"].city,
-                    street,
-                    data["location"].house_number,
-                    data["location"].zip_code,
-                ),
-                CompanyRelationshipEnum.COMPANY,  # type: ignore
-                co_company,
-            )
-            data["relationships"].append(relation)
-    return data
-
-
 def map_unternehmensregister_json(data: dict) -> Company:
     """Processes the Unternehmensregister structured export to a Company by using several helper methods.
 
diff --git a/src/aki_prj23_transparenzregister/utils/data_extraction/unternehmensregister/transform/v3/v3.py b/src/aki_prj23_transparenzregister/utils/data_extraction/unternehmensregister/transform/v3/v3.py
index cdc9981..240231a 100644
--- a/src/aki_prj23_transparenzregister/utils/data_extraction/unternehmensregister/transform/v3/v3.py
+++ b/src/aki_prj23_transparenzregister/utils/data_extraction/unternehmensregister/transform/v3/v3.py
@@ -1,8 +1,6 @@
 """Transform raw Unternehmensregister export (*.xml) to processed .json files for loading."""
 
 import re
-import typing
-from collections.abc import Sequence
 
 from aki_prj23_transparenzregister.models.company import (
     Capital,
@@ -20,6 +18,11 @@ from aki_prj23_transparenzregister.models.company import (
     PersonToCompanyRelationship,
     RelationshipRoleEnum,
 )
+from aki_prj23_transparenzregister.utils.data_extraction.unternehmensregister.transform.common import (
+    map_co_relation,
+    normalize_street,
+    traversal,
+)
 from aki_prj23_transparenzregister.utils.data_extraction.unternehmensregister.transform.v3.role_mapper import (
     RoleMapper,
 )
@@ -193,24 +196,6 @@ def parse_stakeholder(data: dict) -> CompanyRelationship | None:
     return None
 
 
-def normalize_street(street: str) -> str:
-    """Normalize street names by extending them to `Straße` or `straße`.
-
-    Args:
-        street (str): Name of street
-
-    Returns:
-        str: Normalized street name
-    """
-    if street is None:
-        return None
-    regex = r"(Str\.|Strasse)"
-    street = re.sub(regex, "Straße", street)
-    regex = r"(str\.|strasse)"
-    street = re.sub(regex, "straße", street)
-    return street.strip()
-
-
 def loc_from_beteiligung(data: dict) -> Location:
     """Extract the company location from the first relationship in the export.
 
@@ -228,7 +213,6 @@ def loc_from_beteiligung(data: dict) -> Location:
         "tns:beteiligter",
         "tns:auswahl_beteiligter",
         "tns:organisation",
-        # "tns:anschrift",
     ]
     base = traversal(data, base_path)
     base = base["tns:anschrift"] if "tns:anschrift" in base else base["tns:sitz"]
@@ -419,33 +403,6 @@ def map_business_purpose(data: dict) -> str | None:
         return None
 
 
-def extract_date_from_string(value: str) -> str | None:
-    """Extract a date in ISO format from the given string if possible.
-
-    Args:
-        value (str): Input text
-
-    Returns:
-        str | None: Date in ISO format, None if not found
-    """
-    date_regex = [  # type: ignore
-        {"regex": r"\d{1,2}\.\d{1,2}\.\d{4}", "mapper": transform_date_to_iso},
-        {"regex": r"\d{4}-\d{1,2}-\d{1,2}", "mapper": None},
-    ]
-    results = []
-    for regex in date_regex:
-        result = re.findall(regex["regex"], value)  # type: ignore
-        if len(result) == 1:
-            relevant_data = result[0]
-            if regex["mapper"] is not None:  # type: ignore
-                results.append(regex["mapper"](relevant_data))  # type: ignore
-            else:
-                results.append(relevant_data)
-    if len(results) != 1:
-        return None
-    return results[0]
-
-
 def map_founding_date(data: dict) -> str | None:
     """Extracts the founding date from a given Unternehmensregister export.
 
@@ -480,28 +437,6 @@ def map_founding_date(data: dict) -> str | None:
     return None
 
 
-def traversal(data: dict, path: Sequence[str | int | object]) -> typing.Any:
-    """Traverse a dict using list of keys.
-
-    Args:
-        data (dict): Data export
-        path (Sequence[str  |  int  |   object]): List of keys
-
-    Raises:
-        KeyError: If key not found
-
-    Returns:
-        any: Value at the end of the path
-    """
-    current = data
-    for key in path:
-        try:
-            current = current[key]
-        except KeyError as e:
-            raise KeyError(f"Key {key} not found") from e
-    return current
-
-
 def map_hr_number(data: dict) -> str:
     """Extract the HR number from a given Unternehmensregister export.
 
@@ -585,48 +520,7 @@ def map_last_update(data: dict) -> str:
     return traversal(data, path)
 
 
-def map_co_relation(data: dict) -> dict:
-    """Search for and map the c/o relation from location.street if possible.
-
-    Args:
-        data (dict): Company dict
-
-    Returns:
-        dict: Modified Company dict
-    """
-    street = data["location"].street
-    if street is None:
-        return data
-    parts = street.split(",")
-    co_company = None
-    co_company_index = None
-    for index, part in enumerate(parts):
-        trimmed_part = part.strip()
-        result = re.findall(r"^c\/o(.*)$", trimmed_part)
-        if len(result) == 1:
-            co_company = result[0].strip()
-            co_company_index = index
-    if co_company_index is not None:
-        del parts[co_company_index]
-        street = "".join(parts).strip()
-        data["location"].street = street
-
-        if co_company is not None and co_company != "":
-            relation = CompanyToCompanyRelationship(
-                RelationshipRoleEnum.CARE_OF,  # type: ignore
-                Location(
-                    data["location"].city,
-                    street,
-                    data["location"].house_number,
-                    data["location"].zip_code,
-                ),
-                CompanyRelationshipEnum.COMPANY,  # type: ignore
-                co_company,
-            )
-            data["relationships"].append(relation)
-    return data
-
-
+# TODO class model with inheritance - only difference: Determine root in __init__
 def map_unternehmensregister_json(data: dict) -> Company:
     """Processes the Unternehmensregister structured export to a Company by using several helper methods.
 
@@ -651,7 +545,6 @@ def map_unternehmensregister_json(data: dict) -> Company:
     result["business_purpose"] = map_business_purpose(data)
     result["founding_date"] = map_founding_date(data)
 
-    # TODO adapt...
     for i in range(
         2, len(data["tns:grunddaten"]["tns:verfahrensdaten"]["tns:beteiligung"])
     ):
diff --git a/tests/utils/data_extraction/unternehmensregister/transform/common_test.py b/tests/utils/data_extraction/unternehmensregister/transform/common_test.py
new file mode 100644
index 0000000..8a4c5b5
--- /dev/null
+++ b/tests/utils/data_extraction/unternehmensregister/transform/common_test.py
@@ -0,0 +1,144 @@
+"""Testing data_extraction/unternehmensregister/transform/common.py."""
+import pytest
+
+from aki_prj23_transparenzregister.models.company import (
+    CompanyRelationshipEnum,
+    CompanyToCompanyRelationship,
+    Location,
+    RelationshipRoleEnum,
+)
+from aki_prj23_transparenzregister.utils.data_extraction.unternehmensregister.transform import (
+    common,
+)
+
+
+def test_import_common() -> None:
+    assert common
+
+
+def test_traversal() -> None:
+    data = {"a": {"b": {"c": "d"}}}
+    assert common.traversal(data, ["a", "b", "c"]) == "d"
+
+
+# def test_traversal_raises_key_error():
+#     data = {"a": {"b": {"c": "d"}}}
+#     try:
+#         common.traversal(data, ["a", "b", "d"])
+#     except KeyError:
+#         assert True
+#     else:
+#         assert False
+
+
+@pytest.mark.parametrize(
+    ("value", "expected_result"),
+    [
+        (None, None),
+        ("Ludwig-Ganghofer-Str.", "Ludwig-Ganghofer-Straße"),
+        ("Ludwig-Ganghofer-Strasse", "Ludwig-Ganghofer-Straße"),
+        ("Str. des Tests", "Straße des Tests"),
+    ],
+)
+def test_normalize_street(value: str, expected_result: str) -> None:
+    result = common.normalize_street(value)
+    assert result == expected_result
+
+
+@pytest.mark.parametrize(
+    ("value", "expected_result"),
+    [
+        ("", None),
+        ("Tag der ersten Eintragung: 01.05.2004", "2004-05-01"),
+        ("Tag der ersten Eintragung: 1.05.2004", "2004-05-01"),
+        ("Tag der ersten Eintragung: 1.5.2004", "2004-05-01"),
+        ("Tag der ersten Eintragung: 01.5.2004", "2004-05-01"),
+        ("Gesellschaftsvertrag vom 06.04.2016 Hallo Welt", "2016-04-06"),
+        ("Str. des Tests vom 1999-04-05", "1999-04-05"),
+        ("Once upon a midnight dreary while I pondered weak and weary...", None),
+        (
+            "This company was first founded in 2016-06-10 and then again on 1.5.2004",
+            None,
+        ),
+    ],
+)
+def test_extract_date_from_string(value: str, expected_result: str) -> None:
+    result = common.extract_date_from_string(value)
+    assert result == expected_result
+
+
+@pytest.mark.parametrize(
+    ("value", "expected_result"),
+    [
+        (
+            {
+                "location": Location(
+                    "", "c/o Youco24 Business Center, Abc ffda", None, None
+                ),
+                "relationships": [],
+            },
+            {
+                "location": Location("", "Abc ffda", None, None),
+                "relationships": [
+                    CompanyToCompanyRelationship(
+                        RelationshipRoleEnum.CARE_OF,  # type: ignore
+                        Location("", "Abc ffda", None, None),
+                        CompanyRelationshipEnum.COMPANY,
+                        "Youco24 Business Center",
+                    )
+                ],
+            },
+        ),
+        (
+            {
+                "location": Location(
+                    "Iserlohn", "c/o Youco24 Business Center, Abc Str.", "42", "58644"
+                ),
+                "relationships": [],
+            },
+            {
+                "location": Location("Iserlohn", "Abc Str.", "42", "58644"),
+                "relationships": [
+                    CompanyToCompanyRelationship(
+                        RelationshipRoleEnum.CARE_OF,  # type: ignore
+                        Location("Iserlohn", "Abc Str.", "42", "58644"),
+                        CompanyRelationshipEnum.COMPANY,
+                        "Youco24 Business Center",
+                    )
+                ],
+            },
+        ),
+        (
+            {
+                "location": Location(
+                    "Iserlohn", "Abc Str., c/o Youco24 Business Center", "42", "58644"
+                ),
+                "relationships": [],
+            },
+            {
+                "location": Location("Iserlohn", "Abc Str.", "42", "58644"),
+                "relationships": [
+                    CompanyToCompanyRelationship(
+                        RelationshipRoleEnum.CARE_OF,  # type: ignore
+                        Location("Iserlohn", "Abc Str.", "42", "58644"),
+                        CompanyRelationshipEnum.COMPANY,
+                        "Youco24 Business Center",
+                    )
+                ],
+            },
+        ),
+        (
+            {
+                "location": Location("Iserlohn", "Abc Str., c/o", "42", "58644"),
+                "relationships": [],
+            },
+            {
+                "location": Location("Iserlohn", "Abc Str.", "42", "58644"),
+                "relationships": [],
+            },
+        ),
+    ],
+)
+def test_map_co_relation(value: dict, expected_result: dict) -> None:
+    result = common.map_co_relation(value)
+    assert result == expected_result
diff --git a/tests/utils/data_extraction/unternehmensregister/transform/v1_test.py b/tests/utils/data_extraction/unternehmensregister/transform/v1_test.py
index 47c525c..34b8ead 100644
--- a/tests/utils/data_extraction/unternehmensregister/transform/v1_test.py
+++ b/tests/utils/data_extraction/unternehmensregister/transform/v1_test.py
@@ -1,8 +1,6 @@
 """Testing utils/data_extraction/unternehmensregister/transform.py."""
 from unittest.mock import Mock, patch
 
-import pytest
-
 from aki_prj23_transparenzregister.models.company import (
     Capital,
     CapitalTypeEnum,
@@ -266,20 +264,6 @@ def test_loc_from_beteiligung_combine() -> None:
     assert transform.loc_from_beteiligung(data) == expected_result
 
 
-@pytest.mark.parametrize(
-    ("value", "expected_result"),
-    [
-        (None, None),
-        ("Ludwig-Ganghofer-Str.", "Ludwig-Ganghofer-Straße"),
-        ("Ludwig-Ganghofer-Strasse", "Ludwig-Ganghofer-Straße"),
-        ("Str. des Tests", "Straße des Tests"),
-    ],
-)
-def test_normalize_street(value: str, expected_result: str) -> None:
-    result = transform.normalize_street(value)
-    assert result == expected_result
-
-
 def test_name_from_beteiligung() -> None:
     data = {
         "XJustiz_Daten": {
@@ -582,28 +566,6 @@ def test_map_business_purpose_no_result() -> None:
     assert result is None
 
 
-@pytest.mark.parametrize(
-    ("value", "expected_result"),
-    [
-        ("", None),
-        ("Tag der ersten Eintragung: 01.05.2004", "2004-05-01"),
-        ("Tag der ersten Eintragung: 1.05.2004", "2004-05-01"),
-        ("Tag der ersten Eintragung: 1.5.2004", "2004-05-01"),
-        ("Tag der ersten Eintragung: 01.5.2004", "2004-05-01"),
-        ("Gesellschaftsvertrag vom 06.04.2016 Hallo Welt", "2016-04-06"),
-        ("Str. des Tests vom 1999-04-05", "1999-04-05"),
-        ("Once upon a midnight dreary while I pondered weak and weary...", None),
-        (
-            "This company was first founded in 2016-06-10 and then again on 1.5.2004",
-            None,
-        ),
-    ],
-)
-def test_extract_date_from_string(value: str, expected_result: str) -> None:
-    result = transform.extract_date_from_string(value)
-    assert result == expected_result
-
-
 def test_map_founding_date_from_tag_der_ersten_eintragung() -> None:
     data = {
         "some entry": "Tag der ersten Eintragung: 01.05.2004",
@@ -690,83 +652,6 @@ def test_map_last_update() -> None:
     assert result == date
 
 
-@pytest.mark.parametrize(
-    ("value", "expected_result"),
-    [
-        (
-            {
-                "location": Location(
-                    "", "c/o Youco24 Business Center, Abc ffda", None, None
-                ),
-                "relationships": [],
-            },
-            {
-                "location": Location("", "Abc ffda", None, None),
-                "relationships": [
-                    CompanyToCompanyRelationship(
-                        RelationshipRoleEnum.CARE_OF,  # type: ignore
-                        Location("", "Abc ffda", None, None),
-                        CompanyRelationshipEnum.COMPANY,
-                        "Youco24 Business Center",
-                    )
-                ],
-            },
-        ),
-        (
-            {
-                "location": Location(
-                    "Iserlohn", "c/o Youco24 Business Center, Abc Str.", "42", "58644"
-                ),
-                "relationships": [],
-            },
-            {
-                "location": Location("Iserlohn", "Abc Str.", "42", "58644"),
-                "relationships": [
-                    CompanyToCompanyRelationship(
-                        RelationshipRoleEnum.CARE_OF,  # type: ignore
-                        Location("Iserlohn", "Abc Str.", "42", "58644"),
-                        CompanyRelationshipEnum.COMPANY,
-                        "Youco24 Business Center",
-                    )
-                ],
-            },
-        ),
-        (
-            {
-                "location": Location(
-                    "Iserlohn", "Abc Str., c/o Youco24 Business Center", "42", "58644"
-                ),
-                "relationships": [],
-            },
-            {
-                "location": Location("Iserlohn", "Abc Str.", "42", "58644"),
-                "relationships": [
-                    CompanyToCompanyRelationship(
-                        RelationshipRoleEnum.CARE_OF,  # type: ignore
-                        Location("Iserlohn", "Abc Str.", "42", "58644"),
-                        CompanyRelationshipEnum.COMPANY,
-                        "Youco24 Business Center",
-                    )
-                ],
-            },
-        ),
-        (
-            {
-                "location": Location("Iserlohn", "Abc Str., c/o", "42", "58644"),
-                "relationships": [],
-            },
-            {
-                "location": Location("Iserlohn", "Abc Str.", "42", "58644"),
-                "relationships": [],
-            },
-        ),
-    ],
-)
-def test_map_co_relation(value: dict, expected_result: dict) -> None:
-    result = transform.map_co_relation(value)
-    assert result == expected_result
-
-
 @patch(
     "aki_prj23_transparenzregister.utils.data_extraction.unternehmensregister.transform.v1.v1.map_co_relation"
 )