diff --git a/changelog.d/12204.doc b/changelog.d/12204.doc
new file mode 100644
index 000000000..c4b2805bb
--- /dev/null
+++ b/changelog.d/12204.doc
@@ -0,0 +1 @@
+Document that contributors can sign off privately by email.
diff --git a/docs/development/contributing_guide.md b/docs/development/contributing_guide.md
index 844868595..071202e19 100644
--- a/docs/development/contributing_guide.md
+++ b/docs/development/contributing_guide.md
@@ -458,6 +458,17 @@ Git allows you to add this signoff automatically when using the `-s`
 flag to `git commit`, which uses the name and email set in your
 `user.name` and `user.email` git configs.
 
+### Private Sign off
+
+If you would like to provide your legal name privately to the Matrix.org
+Foundation (instead of in a public commit or comment), you can do so
+by emailing your legal name and a link to the pull request to
+[dco@matrix.org](mailto:dco@matrix.org?subject=Private%20sign%20off).
+It helps to include "sign off" or similar in the subject line. You will then
+be instructed further.
+
+Once private sign off is complete, doing so for future contributions will not
+be required.
 
 # 10. Turn feedback into better code.