How do I mark changes to a Creative Commons work?

Mark changes correctly in three steps. Preserve every notice the original creator supplied. Indicate what you changed. Before you choose a licence for the result, test whether your use is an adaptation or a collection.

What Section 3 Demands

Section 3 of every Creative Commons 4.0 license requires you to retain any notice supplied by the licensor, including a copyright notice and a notice referring to the license. That same condition requires you to indicate that you have modified the work. The 4.0 legal code is explicit: you must identify the parts that are adapted and, as far as reasonably practicable, identify the work from which they are adapted. If the licensor supplied a previous modification notice, keep that notice too. The condition does not require a specific format. A plain sentence in your credits line reading “adapted from [title] by [creator], CC BY-SA 4.0” satisfies it, as long as the earlier notices survive intact.

When The Requirement Does Not Apply

The decisive exception is material that is not Adapted Material under the 4.0 definition. A format shift alone, such as converting a JPEG to PNG, does not create Adapted Material and does not trigger the change-marking requirement. Cropping and editing fall into a grey area that depends on applicable copyright law. The 4.0 legal code gives two categorical examples: translation is normally an adaptation, and synchronising music with a moving image is expressly Adapted Material. If your activity is not one of those two, you cannot assume a universal rule applies.

Collections Keep Works Separate

Before you write a single credit line, decide whether your use is an adaptation or a collection. A collection keeps separate works separate. An anthology of unchanged essays under different CC licenses is a collection. Each work retains its own license and its own attribution. You do not replace those licenses with your own. You do not need to mark changes because you are not changing the works.

Adaptations Modify The Source

Adapted Material is based on and modifies the licensed work in a way that requires copyright permission. Remixing a song with new vocals, editing a documentary and adding commentary, or translating a text are adaptations. The adapter’s contribution is covered by the adapter’s license. The original creator’s notices for the source work remain under the source license. Mark the changes and apply a new license to the adaptation, subject to the ND and SA conditions below.

Check Compatibility Before Combining

If you are combining two CC-licensed inputs, check compatibility before you decide anything else. Two inputs can impose incompatible terms even though each uses a CC license. The Creative Commons compatibility chart is the only official source for which licenses satisfy an SA requirement.

If the source work uses a Creative Commons BY-ND 4.0 or BY-NC-ND 4.0 license, you may create Adapted Material for private use only. You are not permitted to share the adaptation under the license. The 4.0 legal code does not prevent you from reproducing the work in a different format alone, because format shifting does not create Adapted Material. But translation and music synchronisation are expressly adaptations, so an ND license blocks sharing those results. If you need to share an adaptation of an ND‑licensed work, obtain separate permission from the licensor.

The SA condition is triggered only when you share Adapted Material. Keep the adaptation private, or share only the unadapted source alongside separate works in a collection, and SA does not apply. The moment you publish the adaptation, the adapter’s license must be the same SA license used by the source or an officially named compatible license. Creative Commons has designated one-way compatibility from CC BY-SA 4.0 to GPLv3 for adapted material. No other license is automatically compatible. Do not assume two SA licenses are compatible. If the source uses CC BY-SA 2.0 Generic and you want to share under BY-SA 4.0, the compatibility list controls whether that is allowed.

Gather What The Source Supplies

Open the original source page and record the creator, the source URL, the exact license and version, and any displayed notice. Write a single credit block that contains the original attribution, the previous modification notice if one exists, and your own statement of change. For a video remix, your credit block might read:

Original footage by Jane Smith, CC BY 4.0. Adapted from [title] at [URL]. Modification: replaced audio track, added new narration. Licensed under CC BY-SA 4.0.

If the original creator included a warranty disclaimer or a specific attribution party, include those as well. The 4.0 license requires you to retain them.

Add The Modification Line

The TASL mnemonic, title, author, source, license, is a useful starting point but does not cover the change-indication requirement. Add the modification line separately.

The Most Common Failure

Check whether the source work itself was an adaptation. If the original already contains a previous modification notice, that notice stays in your credit block. Removing it is a breach of the license condition.