New article: Lower AD DS Domain and Forest Functional Levels (#8116)

* Learn Editor: Update raise-domain-forest-functional-levels.md

* Learn Editor: Update raise-domain-forest-functional-levels.md

* Introducing lower-domain-forest-functional-levels.md

* Apply Deborah Minifie review corrections: raising no longer permanent; Domain Admins can lower domain functional level

* Pre-publish review: add customer intent, refine intro, italicize placeholders with example values, add product brand to title

---------

Co-authored-by: Warren Williams <warrenw@microsoft.com>

Author: robinharwood

WindowsServerDocs/identity/TOC.yml

@@ -459,6 +459,8 @@
               href: ad-ds/manage/Managing-RID-Issuance.md
             - name: Raise domain and forest functional levels
               href: ad-ds/plan/raise-domain-forest-functional-levels.md
+            - name: Lower domain and forest functional levels
+              href: ad-ds/plan/lower-domain-forest-functional-levels.md
             - name: DC locator
               href: ad-ds/manage/dc-locator.md
             - name: Active Directory Forest Recovery Guide

WindowsServerDocs/identity/ad-ds/plan/lower-domain-forest-functional-levels.md

@@ -0,0 +1,104 @@
+---
+title: Lower AD DS Domain and Forest Functional Levels in Windows Server
+description: Learn how to lower the domain or forest functional level in Active Directory Domain Services (AD DS) on Windows Server with PowerShell.
+ms.topic: how-to
+ms.author: roharwoo
+author: robinharwood
+ms.date: 07/03/2026
+ai-usage: ai-assisted
+
+#customer intent: As an AD DS administrator, I want to lower the domain or forest functional level so that I can roll back to a supported earlier level.
+---
+# Lower domain and forest functional levels in Active Directory Domain Services
+
+Functional levels determine the capabilities available in an Active Directory Domain Services (AD DS) domain or forest, and which Windows Server operating systems you can run on domain controllers. You raise a functional level to enable newer capabilities. Raising a level is no longer permanent, so you can lower a domain or forest back to a supported earlier level. You might need to lower the level if you raise it before your environment is ready, or if you need to add domain controllers that run an earlier version of Windows Server.
+
+This article shows how to lower domain and forest functional levels by using PowerShell. After you complete the steps, the domain or forest operates at the level you specify, provided it meets the prerequisites described in this article.
+
+## Prerequisites
+
+Before you lower a functional level, make sure your environment meets the prerequisites in this section.
+
+### Permissions and tools
+
+- To lower the domain functional level, you're a member of the Domain Admins group or have equivalent permissions. To lower the forest functional level, you're a member of the Enterprise Admins group or have equivalent permissions.
+
+- You have a computer with the AD DS Remote Server Administration Tools (RSAT) installed, including the Active Directory module for Windows PowerShell.
+
+### Supported rollback levels
+
+- If your forest or domain contains Windows Server 2022 or earlier domain controllers, the lowest level you can roll back to is Windows Server 2008.
+
+- If your forest or domain contains Windows Server 2025 domain controllers, the lowest level you can roll back to is Windows Server 2016.
+
+### Forest functional level prerequisites
+
+- Your forest doesn't use any forest-level features exclusive to the current functional level. After you enable a feature tied to a specific forest functional level, you can't roll back to a lower level.
+
+- You have access to the domain controller that holds the Schema Operations Master flexible single master operations (FSMO) role.
+
+### Domain functional level prerequisites
+
+- Your domain doesn't use any features exclusive to the current domain functional level. For details about the features each level supports, see [Active Directory Domain Services functional levels](../active-directory-functional-levels.md).
+
+- The target domain functional level isn't lower than the current forest functional level.
+
+- You have network connectivity to the domain controller that holds the Primary Domain Controller (PDC) emulator FSMO role.
+
+## Lower the forest functional level
+
+To lower the forest functional level by using PowerShell:
+
+1. Sign in to a computer with RSAT installed.
+
+1. Open PowerShell as an administrator.
+
+1. Run the following command to lower the forest functional level. Replace *`<forest>`* with the forest name and *`<level>`* with the forest functional level you want. For example, use `Windows2016Forest` to roll back to the Windows Server 2016 level.
+
+   ```powershell
+   Set-ADForestMode -Identity <forest> -ForestMode <level>
+   ```
+
+1. When PowerShell prompts you to confirm, enter **Y**.
+
+1. Run the following command to verify the change.
+
+   ```powershell
+   Get-ADForest | Select-Object ForestMode
+   ```
+
+1. Confirm that `ForestMode` shows the level you set.
+
+## Lower the domain functional level
+
+To lower the domain functional level by using PowerShell:
+
+1. Sign in to a computer with RSAT installed.
+
+1. Open PowerShell as an administrator.
+
+1. Run the following command to lower the domain functional level. Replace *`<domain>`* with the domain name and *`<level>`* with the domain functional level you want. For example, use `Windows2016Domain` to roll back to the Windows Server 2016 level.
+
+   ```powershell
+   Set-ADDomainMode -Identity <domain> -DomainMode <level>
+   ```
+
+1. When PowerShell prompts you to confirm, enter **Y**.
+
+1. Run the following command to verify the change.
+
+   ```powershell
+   Get-ADDomain | Select-Object DomainMode
+   ```
+
+1. Confirm that `DomainMode` shows the level you set.
+
+## Related content
+
+- [Raise domain and forest functional levels in Active Directory Domain Services](raise-domain-forest-functional-levels.md)
+
+- [Active Directory Domain Services functional levels](../active-directory-functional-levels.md)
+
+- [Set-ADDomainMode](/powershell/module/activedirectory/set-addomainmode)
+
+- [Set-ADForestMode](/powershell/module/activedirectory/set-adforestmode)

WindowsServerDocs/identity/ad-ds/plan/raise-domain-forest-functional-levels.md

@@ -16,9 +16,6 @@ To enable the latest forest-wide features, all domain controllers in the forest
 
 The domain and forest functional levels only affect how the domain controllers operate together as a group. The clients that interact with the domain or with the forest are unaffected by the changes. Applications are also unaffected by these changes. However, applications can use new features found in later versions of Windows Server after the administrator raises the domain level. For more information about the functional levels, see [Active Directory Domain Services functional levels](/windows-server/identity/ad-ds/active-directory-functional-levels).
 
-> [!WARNING]
-> Changes to the domain and forest functional levels are irreversible. To undo the change, you must perform a forest recovery to revert to an earlier point in time.
-
 ## Prerequisites
 
 You need to meet the following prerequisites to raise the domain functional level:
@@ -87,9 +84,6 @@ For more information about the `Get-ADDomain` and `Get-ADForest` cmdlets, see [G
 
 To raise the domain and forest functional levels, you can use the Active Directory Domains and Trusts console or Windows PowerShell. The following sections describe how to raise the functional levels by using these methods.
 
-> [!WARNING]
-> Changes to the domain and forest functional levels are irreversible. In order to undo a change, you must perform a forest recovery to revert to an earlier point in time.
-
 > [!IMPORTANT]
 > If all domain controllers in all domains in the forest are running Windows Server 2025, it isn't necessary to raise individual domain functional levels manually because raising the forest functional level to Windows Server 2025 automatically raises the domain functional level of all domains in the forest to Windows Server 2025.
 
@@ -145,6 +139,8 @@ You've now raised the domain and forest functional level. For more information a
 
 ## Related content
 
+- [Lower domain and forest functional levels in Active Directory Domain Services](lower-domain-forest-functional-levels.md)
+
 - [Forest and Domain Functional Levels](../active-directory-functional-levels.md)
 
 - [Identifying Your Functional Level Upgrade](Identifying-Your-Functional-Level-Upgrade.md)