diff --git a/nvdaHelper/local/UIAUtils.cpp b/nvdaHelper/local/UIAUtils.cpp
index f01c86847ba..9a207b32741 100644
--- a/nvdaHelper/local/UIAUtils.cpp
+++ b/nvdaHelper/local/UIAUtils.cpp
@@ -18,3 +18,13 @@ PROPERTYID registerUIAProperty(GUID* guid, LPCWSTR programmaticName, UIAutomatio
 	registrar->Release();
 	return propertyId;
 }
+
+int registerUIAAnnotationType(GUID* guid) {
+	if(!guid) {
+		LOG_DEBUGWARNING(L"NULL GUID given");
+		return 0;
+	}
+	winrt::Windows::UI::UIAutomation::Core::CoreAutomationRegistrar registrar {};
+	auto res = registrar.RegisterAnnotationType(*guid);
+	return res.LocalId;
+}
diff --git a/nvdaHelper/local/UIAUtils.h b/nvdaHelper/local/UIAUtils.h
index b0229e806f7..13807960af1 100644
--- a/nvdaHelper/local/UIAUtils.h
+++ b/nvdaHelper/local/UIAUtils.h
@@ -1,9 +1,15 @@
 #ifndef NVDAHELPERLOCAL_UIAUTILS_H
 #define NVDAHELPERLOCAL_UIAUTILS_H
 
+// The following header included to allow winrt::guid to be converted to GUID
+#include <unknwn.h>
+
+#include <winrt/windows.ui.uiautomation.core.h>
 #include <uiAutomationCore.h>
 
 PROPERTYID registerUIAProperty(GUID* guid, LPCWSTR programmaticName, UIAutomationType propertyType);
+int registerUIAAnnotationType(GUID* guid);
+
 
 #endif
 
diff --git a/nvdaHelper/local/nvdaHelperLocal.def b/nvdaHelper/local/nvdaHelperLocal.def
index 8735a7e61e3..7c700b58506 100644
--- a/nvdaHelper/local/nvdaHelperLocal.def
+++ b/nvdaHelper/local/nvdaHelperLocal.def
@@ -55,6 +55,7 @@ EXPORTS
 	calculateCharacterOffsets
 	findWindowWithClassInThread
 	registerUIAProperty
+	registerUIAAnnotationType
 	dllImportTableHooks_hookSingle
 	dllImportTableHooks_unhookSingle
 	audioDucking_shouldDelay
diff --git a/source/NVDAObjects/UIA/__init__.py b/source/NVDAObjects/UIA/__init__.py
index 28fd25676b7..6ae7ceee419 100644
--- a/source/NVDAObjects/UIA/__init__.py
+++ b/source/NVDAObjects/UIA/__init__.py
@@ -17,6 +17,7 @@
 import languageHandler
 import UIAHandler
 import _UIACustomProps
+import _UIACustomAnnotations
 import globalVars
 import eventHandler
 import controlTypes
@@ -818,6 +819,7 @@ def updateSelection(self):
 
 class UIA(Window):
 	_UIACustomProps = _UIACustomProps.CustomPropertiesCommon.get()
+	_UIACustomAnnotationTypes = _UIACustomAnnotations.CustomAnnotationTypesCommon.get()
 
 	shouldAllowDuplicateUIAFocusEvent = False
 
diff --git a/source/NVDAObjects/UIA/excel.py b/source/NVDAObjects/UIA/excel.py
index e4c0d85a296..3b89e40b75b 100644
--- a/source/NVDAObjects/UIA/excel.py
+++ b/source/NVDAObjects/UIA/excel.py
@@ -4,6 +4,8 @@
 # Copyright (C) 2018-2021 NV Access Limited, Leonard de Ruijter
 
 from typing import Optional, Tuple
+from comtypes import COMError
+import winVersion
 import UIAHandler
 import _UIAHandler
 import _UIAConstants
@@ -16,6 +18,9 @@
 from _UIACustomProps import (
 	CustomPropertyInfo,
 )
+from _UIACustomAnnotations import (
+	CustomAnnotationTypeInfo,
+)
 from comtypes import GUID
 from scriptHandler import script
 import ui
@@ -90,10 +95,35 @@ def __init__(self):
 		)
 
 
+class ExcelCustomAnnotationTypes:
+	""" UIA 'custom annotation types' specific to Excel.
+	Once registered, all subsequent registrations will return the same ID value.
+	This class should be used as a singleton via ExcelCustomAnnotationTypes.get()
+	to prevent unnecessary work by repeatedly interacting with UIA.
+	"""
+	#: Singleton instance
+	_instance: "Optional[ExcelCustomAnnotationTypes]" = None
+
+	@classmethod
+	def get(cls) -> "ExcelCustomAnnotationTypes":
+		"""Get the singleton instance or initialise it.
+		"""
+		if cls._instance is None:
+			cls._instance = cls()
+		return cls._instance
+
+	def __init__(self):
+		self.note = CustomAnnotationTypeInfo(
+			guid=GUID("{4E863D9A-F502-4A67-808F-9E711702D05E}"),
+		)
+
+
 class ExcelObject(UIA):
 	"""Common base class for all Excel UIA objects
 	"""
 	_UIAExcelCustomProps = ExcelCustomProperties.get()
+	_UIAExcelCustomAnnotationTypes = ExcelCustomAnnotationTypes.get()
+
 
 
 class ExcelCell(ExcelObject):
@@ -367,6 +397,15 @@ def _get_states(self):
 			states.add(controlTypes.State.HASFORMULA)
 		if self._getUIACacheablePropertyValue(self._UIAExcelCustomProps.hasDataValidationDropdown.id):
 			states.add(controlTypes.State.HASPOPUP)
+		if winVersion.getWinVer() >= winVersion.WIN11:
+			try:
+				annotationTypes = self._getUIACacheablePropertyValue(UIAHandler.UIA_AnnotationTypesPropertyId)
+			except COMError:
+				# annotationTypes cannot be fetched on older Operating Systems such as Windows 7.
+				annotationTypes = None
+			if annotationTypes:
+				if self._UIAExcelCustomAnnotationTypes.note.id in annotationTypes:
+					states.add(controlTypes.State.HASNOTE)
 		return states
 
 	def _get_cellCoordsText(self):
@@ -421,6 +460,17 @@ def _get_cellCoordsText(self):
 		description=_("Reports the note or comment thread on the current cell"),
 		gesture="kb:NVDA+alt+c")
 	def script_reportComment(self, gesture):
+		if winVersion.getWinVer() >= winVersion.WIN11:
+			noteElement = self.UIAAnnotationObjects.get(self._UIAExcelCustomAnnotationTypes.note.id)
+			if noteElement:
+				name = noteElement.CurrentName
+				desc = noteElement.GetCurrentPropertyValue(UIAHandler.UIA_FullDescriptionPropertyId)
+				# Translators: a note on a cell in Microsoft excel.
+				text = _("{name}: {desc}").format(name=name, desc=desc)
+				ui.message(text)
+			else:
+				# Translators: message when a cell in Excel contains no note
+				ui.message(_("No note on this cell"))
 		commentsElement = self.UIAAnnotationObjects.get(UIAHandler.AnnotationType_Comment)
 		if commentsElement:
 			comment = commentsElement.GetCurrentPropertyValue(UIAHandler.UIA_FullDescriptionPropertyId)
@@ -428,21 +478,21 @@ def script_reportComment(self, gesture):
 			numReplies = commentsElement.GetCurrentPropertyValue(self._UIAExcelCustomProps.commentReplyCount.id)
 			if numReplies == 0:
 				# Translators: a comment on a cell in Microsoft excel.
-				text = _("{comment}  by {author}").format(
+				text = _("Comment thread: {comment}  by {author}").format(
 					comment=comment,
 					author=author
 				)
 			else:
 				# Translators: a comment on a cell in Microsoft excel.
-				text = _("{comment}  by {author} with {numReplies} replies").format(
+				text = _("Comment thread: {comment}  by {author} with {numReplies} replies").format(
 					comment=comment,
 					author=author,
 					numReplies=numReplies
 				)
 			ui.message(text)
 		else:
-			# Translators: A message in Excel when there is no note
-			ui.message(_("No note or comment thread on this cell"))
+			# Translators: A message in Excel when there is no comment thread
+			ui.message(_("No comment thread on this cell"))
 
 
 class ExcelWorksheet(ExcelObject):
diff --git a/source/_UIACustomAnnotations.py b/source/_UIACustomAnnotations.py
new file mode 100644
index 00000000000..7187441b6b0
--- /dev/null
+++ b/source/_UIACustomAnnotations.py
@@ -0,0 +1,80 @@
+# A part of NonVisual Desktop Access (NVDA)
+# Copyright (C) 2021 NV Access Limited
+# This file is covered by the GNU General Public License.
+# See the file COPYING for more details.
+
+from dataclasses import (
+	dataclass,
+	field,
+)
+from typing import Optional
+
+from comtypes import (
+	GUID,
+	byref,
+)
+import winVersion
+
+
+"""
+This module provides helpers and a common format to define UIA custom annotation types.
+The common custom annotation types are defined here.
+Custom annotation types specific to an application should be defined within a NVDAObjects/UIA
+submodule specific to that application, E.G. 'NVDAObjects/UIA/excel.py'
+
+UIA originally had hard coded 'static' ID's for annotation types.
+For an example see 'AnnotationType_SpellingError' in
+`source/comInterfaces/_944DE083_8FB8_45CF_BCB7_C477ACB2F897_0_1_0.py`
+imported via `UIAutomationClient.py`.
+When a new annotation type was added the UIA spec had to be updated.
+Now a mechanism is in place to allow applications to register "custom annotation types".
+This relies on both the UIA server application and the UIA client application sharing a known
+GUID for the annotation type.
+"""
+
+
+@dataclass
+class CustomAnnotationTypeInfo:
+	"""Holds information about a CustomAnnotationType
+	This makes it easy to define custom annotation types to be loaded.
+	"""
+	guid: GUID
+	id: int = field(init=False)
+
+	def __post_init__(self) -> None:
+		""" The id field must be initialised at runtime.
+		A GUID uniquely identifies a custom annotation, but the UIA system relies on integer IDs.
+		Any application (clients or providers) can register a custom annotation type, subsequent applications
+		will get the same id for a given GUID.
+		Registering custom annotations is only supported on Windows 11 and above.
+		For any lesser version, id will be 0.
+
+		"""
+		if winVersion.getWinVer() >= winVersion.WIN11:
+			import NVDAHelper
+			self.id = NVDAHelper.localLib.registerUIAAnnotationType(
+				byref(self.guid),
+			)
+		else:
+			self.id = 0
+
+
+class CustomAnnotationTypesCommon:
+	"""UIA 'custom annotation types' common to all applications.
+	Once registered, all subsequent registrations will return the same ID value.
+	This class should be used as a singleton via CustomAnnotationTypesCommon.get()
+	to prevent unnecessary work by repeatedly interacting with UIA.
+	"""
+	#: Singleton instance
+	_instance: "Optional[CustomAnnotationTypesCommon]" = None
+
+	@classmethod
+	def get(cls) -> "CustomAnnotationTypesCommon":
+		"""Get the singleton instance or initialise it.
+		"""
+		if cls._instance is None:
+			cls._instance = cls()
+		return cls._instance
+
+	def __init__(self):
+		pass
diff --git a/source/controlTypes/state.py b/source/controlTypes/state.py
index 29b792bbc1f..e32f8addbc1 100644
--- a/source/controlTypes/state.py
+++ b/source/controlTypes/state.py
@@ -71,6 +71,7 @@ def negativeDisplayString(self) -> str:
 	OVERFLOWING = 0x10000000000
 	UNLOCKED = 0x20000000000
 	HAS_ARIA_DETAILS = 0x40000000000
+	HASNOTE = 0x80000000000
 
 
 STATES_SORTED = frozenset([State.SORTED, State.SORTED_ASCENDING, State.SORTED_DESCENDING])
@@ -160,6 +161,8 @@ def negativeDisplayString(self) -> str:
 	# Translators: a state that denotes that the object is unlocked (such as an unlocked cell in a protected
 	# Excel spreadsheet).
 	State.UNLOCKED: _("unlocked"),
+	# Translators: a state that denotes the existance of a note.
+	State.HASNOTE: _("has note"),
 }