diff --git a/pontos/updateheader/_parser.py b/pontos/updateheader/_parser.py
index 7315ae646..577f5d0c2 100644
--- a/pontos/updateheader/_parser.py
+++ b/pontos/updateheader/_parser.py
@@ -114,8 +114,8 @@ def parse_args(args: Optional[Sequence[str]] = None) -> Namespace:
         action="store_true",
         default=False,
         help=(
-            "If set, will not update license with from-to years format "
-            "(YYYY-YYYY) if it has single (only creation) year format (YYYY). "
+            "If set, will format license headers in from-to year format "
+            "into single (creation) year format. "
             "Default is %(default)s."
         ),
     )
diff --git a/pontos/updateheader/updateheader.py b/pontos/updateheader/updateheader.py
index 5339436c9..9f70ede94 100644
--- a/pontos/updateheader/updateheader.py
+++ b/pontos/updateheader/updateheader.py
@@ -8,6 +8,7 @@
 Also it appends a header if it is missing in the file.
 """
 
+import io
 import re
 import sys
 from dataclasses import dataclass
@@ -208,39 +209,43 @@ def update_file(
                 return
 
             # replace found header and write it to file
-            if copyright_match and (
-                not copyright_match.modification_year
-                and copyright_match.creation_year < year
-                or copyright_match.modification_year
-                and copyright_match.modification_year < year
-            ):
+            if copyright_match:
+
+                # use different target license formats depending on provided single_year argument
                 if single_year:
-                    # In case of single year updating the license with modification date doesn't make sense.
-                    # Changing the existing license header with created-modified years to single year is not supported.
-                    return
-                copyright_term = (
-                    f"SPDX-FileCopyrightText: "
-                    f"{copyright_match.creation_year}"
-                    f"-{year} {company}"
-                )
-                new_line = re.sub(copyright_regex, copyright_term, line)
-                fp_write = fp.tell() - len(line)  # save position to insert
-                rest_of_file = fp.read()
-                fp.seek(fp_write)
-                fp.write(new_line)
-                fp.write(rest_of_file)
-                # in some cases we replace "YYYY - YYYY" with "YYYY-YYYY"
-                # resulting in 2 characters left at the end of the file
-                # so we truncate the file, just in case!
-                fp.truncate()
-                print(
-                    f"{file}: Changed License Header Copyright Year "
-                    f"{copyright_match.modification_year} -> "
-                    f"{year}"
-                )
+                    copyright_term = (
+                        f"SPDX-FileCopyrightText: "
+                        f"{copyright_match.creation_year} "
+                        f"{company}"
+                    )
+                else:
+                    copyright_term = (
+                        f"SPDX-FileCopyrightText: "
+                        f"{copyright_match.creation_year}"
+                        f"-{year} {company}"
+                    )
+
+                with_multi_year = copyright_match.creation_year and copyright_match.modification_year
+                with_single_year_outdated = not copyright_match.modification_year and copyright_match.creation_year < year
+                with_multi_year_outdated = with_multi_year and copyright_match.modification_year < year
+
+                if single_year and with_multi_year:
+                    _substitute_license_text(fp, line, copyright_regex, copyright_term)
+                    print(
+                        f"{file}: Changed License Header Copyright Year format to single year "
+                        f"{copyright_match.creation_year}-{year} -> "
+                        f"{copyright_match.creation_year}"
+                    )
+                elif not single_year and (with_multi_year_outdated or with_single_year_outdated):
+                    _substitute_license_text(fp, line, copyright_regex, copyright_term)
+                    print(
+                        f"{file}: Changed License Header Copyright Year "
+                        f"{copyright_match.modification_year} -> "
+                        f"{year}"
+                    )
+                else:
+                    print(f"{file}: License Header is ok.")
 
-            else:
-                print(f"{file}: License Header is ok.")
     except FileNotFoundError as e:
         print(f"{file}: File is not existing.")
         raise e
@@ -258,6 +263,25 @@ def update_file(
             print(f"{file}: Cleaned up!")
 
 
+def _substitute_license_text(
+    fp: io.TextIOWrapper,
+    line: str,
+    copyright_regex: re.Pattern,
+    copyright_term: str,
+) -> None:
+    """Substitute the old license text in file fp, starting on provided line, with the new one provided in copyright_term"""
+    new_line = re.sub(copyright_regex, copyright_term, line)
+    fp_write = fp.tell() - len(line)  # save position to insert
+    rest_of_file = fp.read()
+    fp.seek(fp_write)
+    fp.write(new_line)
+    fp.write(rest_of_file)
+    # in some cases we replace "YYYY - YYYY" with "YYYY-YYYY"
+    # resulting in 2 characters left at the end of the file
+    # so we truncate the file, just in case!
+    fp.truncate()
+
+
 def _get_exclude_list(
     exclude_file: Path, directories: list[Path]
 ) -> list[Path]:
diff --git a/tests/updateheader/test_header.py b/tests/updateheader/test_header.py
index e00b48bb4..59dfe8e7b 100644
--- a/tests/updateheader/test_header.py
+++ b/tests/updateheader/test_header.py
@@ -343,7 +343,7 @@ def test_update_header_in_file_single_year(self, mock_stdout):
         year = "2021"
         license_id = "AGPL-3.0-or-later"
 
-        header = HEADER.format(date="2020")
+        header = HEADER.format(date="2020-2021")
         with temp_file(
             content=header, name="test.py", change_into=True
         ) as test_file:
@@ -355,6 +355,13 @@ def test_update_header_in_file_single_year(self, mock_stdout):
                 single_year=True,
             )
 
+            ret = mock_stdout.getvalue()
+            self.assertEqual(
+                ret,
+                f"{test_file}: Changed License Header Copyright Year format to single year "
+                "2020-2021 -> 2020\n",
+            )
+
             self.assertIn(
                 "# SPDX-FileCopyrightText: 2020 Greenbone AG",
                 test_file.read_text(encoding="utf-8"),