diff --git a/txnbuild/CHANGELOG.md b/txnbuild/CHANGELOG.md
index d7ed9c8cd1..82839d1711 100644
--- a/txnbuild/CHANGELOG.md
+++ b/txnbuild/CHANGELOG.md
@@ -6,6 +6,16 @@ file.  This project adheres to [Semantic Versioning](http://semver.org/).
 
 ## Unreleased
 
+### Breaking changes
+
+* Muxed accounts and ID memos can be used in the `BuildChallengeTx()` and `ReadChallengeTx()` SEP-10 utilitiy functions to identify users of shared Stellar accounts. ([#4746](https://github.com/stellar/go/pull/4746))
+  * `BuildChallengeTx()`:
+    * Muxed account addresses can be passed as the `clientAccountID`.
+    * Adds an additional parameter of type `txnbuild.Memo`. Memos must be of type ID and cannot be specified if the `clientAccoutID` id a muxed account address.
+  * `ReadChallengeTx()`:
+    * Muxed account addresses may be returned as the `clientAccountID`.
+    * Adds an additional return value of type `txnbuild.Memo`, which if non-nil, will always be a memo of type ID.
+
 
 ## [10.0.0](https://github.com/stellar/go/releases/tag/horizonclient-v9.0.0) - 2022-04-18