diff --git a/fpdfsdk/cpdfsdk_annothandlermgr.cpp b/fpdfsdk/cpdfsdk_annothandlermgr.cpp
index e5e0313..891e950 100644
--- a/fpdfsdk/cpdfsdk_annothandlermgr.cpp
+++ b/fpdfsdk/cpdfsdk_annothandlermgr.cpp
@@ -231,19 +231,35 @@
   return GetAnnotHandler(pAnnot)->OnChar(pAnnot, nChar, nFlags);
 }
 
-bool CPDFSDK_AnnotHandlerMgr::Annot_OnKeyDown(CPDFSDK_Annot* pAnnot,
+bool CPDFSDK_AnnotHandlerMgr::Annot_OnKeyDown(CPDFSDK_PageView* pPageView,
+                                              CPDFSDK_Annot* pAnnot,
                                               int nKeyCode,
                                               int nFlag) {
+  if (!pAnnot) {
+    // If pressed key is not tab then no action is needed.
+    if (nKeyCode != FWL_VKEY_Tab)
+      return false;
+
+    // If ctrl key or alt key is pressed, then no action is needed.
+    if (CPWL_Wnd::IsCTRLKeyDown(nFlag) || CPWL_Wnd::IsALTKeyDown(nFlag))
+      return false;
+
+    ObservedPtr<CPDFSDK_Annot> end_annot(GetFirstOrLastFocusableAnnot(
+        pPageView, CPWL_Wnd::IsSHIFTKeyDown(nFlag)));
+    return end_annot && pPageView->GetFormFillEnv()->SetFocusAnnot(&end_annot);
+  }
+
   if (CPWL_Wnd::IsCTRLKeyDown(nFlag) || CPWL_Wnd::IsALTKeyDown(nFlag)) {
     return GetAnnotHandler(pAnnot)->OnKeyDown(pAnnot, nKeyCode, nFlag);
   }
   ObservedPtr<CPDFSDK_Annot> pObservedAnnot(pAnnot);
-  CPDFSDK_PageView* pPageView = pAnnot->GetPageView();
   CPDFSDK_Annot* pFocusAnnot = pPageView->GetFocusAnnot();
   if (pFocusAnnot && (nKeyCode == FWL_VKEY_Tab)) {
     ObservedPtr<CPDFSDK_Annot> pNext(
         GetNextAnnot(pFocusAnnot, !CPWL_Wnd::IsSHIFTKeyDown(nFlag)));
-    if (pNext && pNext.Get() != pFocusAnnot) {
+    if (!pNext)
+      return false;
+    if (pNext.Get() != pFocusAnnot) {
       pPageView->GetFormFillEnv()->SetFocusAnnot(&pNext);
       return true;
     }
@@ -333,3 +349,20 @@
                            pFormFillEnv->GetFocusableAnnotSubtypes());
   return bNext ? ai.GetNextAnnot(pSDKAnnot) : ai.GetPrevAnnot(pSDKAnnot);
 }
+
+CPDFSDK_Annot* CPDFSDK_AnnotHandlerMgr::GetFirstOrLastFocusableAnnot(
+    CPDFSDK_PageView* page_view,
+    bool last) const {
+#ifdef PDF_ENABLE_XFA
+  IPDF_Page* page = page_view->GetXFAPage();
+  if (page && !page->AsPDFPage()) {
+    // For XFA annots in XFA pages not backed by PDF pages.
+    return page->AsXFAPage()->GetFirstOrLastXFAAnnot(page_view, last);
+  }
+#endif  // PDF_ENABLE_XFA
+
+  CPDFSDK_FormFillEnvironment* form_fill_env = page_view->GetFormFillEnv();
+  CPDFSDK_AnnotIterator ai(page_view,
+                           form_fill_env->GetFocusableAnnotSubtypes());
+  return last ? ai.GetLastAnnot() : ai.GetFirstAnnot();
+}
diff --git a/fpdfsdk/cpdfsdk_annothandlermgr.h b/fpdfsdk/cpdfsdk_annothandlermgr.h
index cc3f715..a103469 100644
--- a/fpdfsdk/cpdfsdk_annothandlermgr.h
+++ b/fpdfsdk/cpdfsdk_annothandlermgr.h
@@ -97,7 +97,10 @@
                          uint32_t nFlags,
                          const CFX_PointF& point);
   bool Annot_OnChar(CPDFSDK_Annot* pAnnot, uint32_t nChar, uint32_t nFlags);
-  bool Annot_OnKeyDown(CPDFSDK_Annot* pAnnot, int nKeyCode, int nFlag);
+  bool Annot_OnKeyDown(CPDFSDK_PageView* pPageView,
+                       CPDFSDK_Annot* pAnnot,
+                       int nKeyCode,
+                       int nFlag);
   bool Annot_OnSetFocus(ObservedPtr<CPDFSDK_Annot>* pAnnot, uint32_t nFlag);
   bool Annot_OnKillFocus(ObservedPtr<CPDFSDK_Annot>* pAnnot, uint32_t nFlag);
   bool Annot_SetIndexSelected(ObservedPtr<CPDFSDK_Annot>* pAnnot,
@@ -123,6 +126,8 @@
   IPDFSDK_AnnotHandler* GetAnnotHandlerOfType(
       CPDF_Annot::Subtype nAnnotSubtype) const;
   CPDFSDK_Annot* GetNextAnnot(CPDFSDK_Annot* pSDKAnnot, bool bNext);
+  CPDFSDK_Annot* GetFirstOrLastFocusableAnnot(CPDFSDK_PageView* page_view,
+                                              bool last) const;
 
   // |m_pBAAnnotHandler| and |m_pWidgetHandler| are always present, but
   // |m_pXFAWidgetHandler| is only present in XFA mode.
diff --git a/fpdfsdk/cpdfsdk_annotiterator.cpp b/fpdfsdk/cpdfsdk_annotiterator.cpp
index c1db6bb..1e0867a 100644
--- a/fpdfsdk/cpdfsdk_annotiterator.cpp
+++ b/fpdfsdk/cpdfsdk_annotiterator.cpp
@@ -70,16 +70,14 @@
     return nullptr;
   ++iter;
   if (iter == m_Annots.end())
-    iter = m_Annots.begin();
+    return nullptr;
   return *iter;
 }
 
 CPDFSDK_Annot* CPDFSDK_AnnotIterator::GetPrevAnnot(CPDFSDK_Annot* pAnnot) {
   auto iter = std::find(m_Annots.begin(), m_Annots.end(), pAnnot);
-  if (iter == m_Annots.end())
+  if (iter == m_Annots.begin() || iter == m_Annots.end())
     return nullptr;
-  if (iter == m_Annots.begin())
-    iter = m_Annots.end();
   return *(--iter);
 }
 
diff --git a/fpdfsdk/cpdfsdk_annotiterator_embeddertest.cpp b/fpdfsdk/cpdfsdk_annotiterator_embeddertest.cpp
index 651e46b..556eb8b 100644
--- a/fpdfsdk/cpdfsdk_annotiterator_embeddertest.cpp
+++ b/fpdfsdk/cpdfsdk_annotiterator_embeddertest.cpp
@@ -55,7 +55,7 @@
     pAnnot = iter.GetNextAnnot(pAnnot);
     CheckRect(pAnnot->GetRect(), LeftBottom);
     pAnnot = iter.GetNextAnnot(pAnnot);
-    EXPECT_EQ(iter.GetFirstAnnot(), pAnnot);
+    EXPECT_EQ(nullptr, pAnnot);
 
     pAnnot = iter.GetLastAnnot();
     CheckRect(pAnnot->GetRect(), LeftBottom);
@@ -66,7 +66,7 @@
     pAnnot = iter.GetPrevAnnot(pAnnot);
     CheckRect(pAnnot->GetRect(), RightTop);
     pAnnot = iter.GetPrevAnnot(pAnnot);
-    EXPECT_EQ(iter.GetLastAnnot(), pAnnot);
+    EXPECT_EQ(nullptr, pAnnot);
   }
   {
     // Page 1 specifies "column order"
@@ -81,7 +81,7 @@
     pAnnot = iter.GetNextAnnot(pAnnot);
     CheckRect(pAnnot->GetRect(), LeftBottom);
     pAnnot = iter.GetNextAnnot(pAnnot);
-    EXPECT_EQ(iter.GetFirstAnnot(), pAnnot);
+    EXPECT_EQ(nullptr, pAnnot);
 
     pAnnot = iter.GetLastAnnot();
     CheckRect(pAnnot->GetRect(), LeftBottom);
@@ -92,7 +92,7 @@
     pAnnot = iter.GetPrevAnnot(pAnnot);
     CheckRect(pAnnot->GetRect(), RightTop);
     pAnnot = iter.GetPrevAnnot(pAnnot);
-    EXPECT_EQ(iter.GetLastAnnot(), pAnnot);
+    EXPECT_EQ(nullptr, pAnnot);
   }
   {
     // Page 2 specifies "struct order"
@@ -107,7 +107,7 @@
     pAnnot = iter.GetNextAnnot(pAnnot);
     CheckRect(pAnnot->GetRect(), RightBottom);
     pAnnot = iter.GetNextAnnot(pAnnot);
-    EXPECT_EQ(iter.GetFirstAnnot(), pAnnot);
+    EXPECT_EQ(nullptr, pAnnot);
 
     pAnnot = iter.GetLastAnnot();
     CheckRect(pAnnot->GetRect(), RightBottom);
@@ -118,7 +118,7 @@
     pAnnot = iter.GetPrevAnnot(pAnnot);
     CheckRect(pAnnot->GetRect(), LeftBottom);
     pAnnot = iter.GetPrevAnnot(pAnnot);
-    EXPECT_EQ(iter.GetLastAnnot(), pAnnot);
+    EXPECT_EQ(nullptr, pAnnot);
   }
   UnloadPage(page2);
   UnloadPage(page1);
diff --git a/fpdfsdk/cpdfsdk_pageview.cpp b/fpdfsdk/cpdfsdk_pageview.cpp
index 45b3ffa..e63fca6 100644
--- a/fpdfsdk/cpdfsdk_pageview.cpp
+++ b/fpdfsdk/cpdfsdk_pageview.cpp
@@ -467,12 +467,10 @@
 }
 
 bool CPDFSDK_PageView::OnKeyDown(int nKeyCode, int nFlag) {
-  if (CPDFSDK_Annot* pAnnot = GetFocusAnnot()) {
-    CPDFSDK_AnnotHandlerMgr* pAnnotHandlerMgr =
-        m_pFormFillEnv->GetAnnotHandlerMgr();
-    return pAnnotHandlerMgr->Annot_OnKeyDown(pAnnot, nKeyCode, nFlag);
-  }
-  return false;
+  CPDFSDK_AnnotHandlerMgr* pAnnotHandlerMgr =
+      m_pFormFillEnv->GetAnnotHandlerMgr();
+  return pAnnotHandlerMgr->Annot_OnKeyDown(this, GetFocusAnnot(), nKeyCode,
+                                           nFlag);
 }
 
 bool CPDFSDK_PageView::OnKeyUp(int nKeyCode, int nFlag) {
diff --git a/fpdfsdk/fpdf_formfill_embeddertest.cpp b/fpdfsdk/fpdf_formfill_embeddertest.cpp
index af0df63..d9c33fe 100644
--- a/fpdfsdk/fpdf_formfill_embeddertest.cpp
+++ b/fpdfsdk/fpdf_formfill_embeddertest.cpp
@@ -727,6 +727,181 @@
     UnloadPage(page);
 }
 
+TEST_F(FPDFFormFillEmbedderTest, FormFillFirstTab) {
+  ASSERT_TRUE(OpenDocument("annotiter.pdf"));
+  FPDF_PAGE page = LoadPage(0);
+  ASSERT_TRUE(page);
+
+  // Invoking first tab on the page.
+  ASSERT_TRUE(FORM_OnKeyDown(form_handle(), page, FWL_VKEY_Tab, 0));
+  int page_index = -2;
+  FPDF_ANNOTATION annot = nullptr;
+  EXPECT_TRUE(FORM_GetFocusedAnnot(form_handle(), &page_index, &annot));
+  EXPECT_EQ(0, page_index);
+  ASSERT_TRUE(annot);
+  EXPECT_EQ(1, FPDFPage_GetAnnotIndex(page, annot));
+  FPDFPage_CloseAnnot(annot);
+
+  UnloadPage(page);
+}
+
+TEST_F(FPDFFormFillEmbedderTest, FormFillFirstShiftTab) {
+  ASSERT_TRUE(OpenDocument("annotiter.pdf"));
+  FPDF_PAGE page = LoadPage(0);
+  ASSERT_TRUE(page);
+
+  // Invoking first shift-tab on the page.
+  ASSERT_TRUE(FORM_OnKeyDown(form_handle(), page, FWL_VKEY_Tab,
+                             FWL_EVENTFLAG_ShiftKey));
+  int page_index = -2;
+  FPDF_ANNOTATION annot = nullptr;
+  EXPECT_TRUE(FORM_GetFocusedAnnot(form_handle(), &page_index, &annot));
+  EXPECT_EQ(0, page_index);
+  ASSERT_TRUE(annot);
+  EXPECT_EQ(0, FPDFPage_GetAnnotIndex(page, annot));
+  FPDFPage_CloseAnnot(annot);
+
+  UnloadPage(page);
+}
+
+TEST_F(FPDFFormFillEmbedderTest, FormFillContinuousTab) {
+  ASSERT_TRUE(OpenDocument("annotiter.pdf"));
+  FPDF_PAGE page = LoadPage(0);
+  ASSERT_TRUE(page);
+
+  static constexpr int kExpectedAnnotIndex[] = {1, 2, 3, 0};
+  // Tabs should iterate focus over annotations.
+  for (size_t i = 0; i < FX_ArraySize(kExpectedAnnotIndex); ++i) {
+    ASSERT_TRUE(FORM_OnKeyDown(form_handle(), page, FWL_VKEY_Tab, 0));
+    int page_index = -2;
+    FPDF_ANNOTATION annot = nullptr;
+    EXPECT_TRUE(FORM_GetFocusedAnnot(form_handle(), &page_index, &annot));
+    EXPECT_EQ(0, page_index);
+    ASSERT_TRUE(annot);
+    EXPECT_EQ(kExpectedAnnotIndex[i], FPDFPage_GetAnnotIndex(page, annot));
+    FPDFPage_CloseAnnot(annot);
+  }
+
+  // Tab should not be handled as the last annotation of the page is in focus.
+  ASSERT_FALSE(FORM_OnKeyDown(form_handle(), page, FWL_VKEY_Tab, 0));
+
+  UnloadPage(page);
+}
+
+TEST_F(FPDFFormFillEmbedderTest, FormFillContinuousShiftTab) {
+  ASSERT_TRUE(OpenDocument("annotiter.pdf"));
+  FPDF_PAGE page = LoadPage(0);
+  ASSERT_TRUE(page);
+
+  static constexpr int kExpectedAnnotIndex[] = {0, 3, 2, 1};
+  // Shift-tabs should iterate focus over annotations.
+  for (size_t i = 0; i < FX_ArraySize(kExpectedAnnotIndex); ++i) {
+    ASSERT_TRUE(FORM_OnKeyDown(form_handle(), page, FWL_VKEY_Tab,
+                               FWL_EVENTFLAG_ShiftKey));
+    int page_index = -2;
+    FPDF_ANNOTATION annot = nullptr;
+    EXPECT_TRUE(FORM_GetFocusedAnnot(form_handle(), &page_index, &annot));
+    EXPECT_EQ(0, page_index);
+    ASSERT_TRUE(annot);
+    EXPECT_EQ(kExpectedAnnotIndex[i], FPDFPage_GetAnnotIndex(page, annot));
+    FPDFPage_CloseAnnot(annot);
+  }
+
+  // Shift-tab should not be handled as the first annotation of the page is in
+  // focus.
+  ASSERT_FALSE(FORM_OnKeyDown(form_handle(), page, FWL_VKEY_Tab,
+                              FWL_EVENTFLAG_ShiftKey));
+
+  UnloadPage(page);
+}
+
+TEST_F(FPDFFormFillEmbedderTest, TabWithModifiers) {
+  EXPECT_TRUE(OpenDocument("annotiter.pdf"));
+  FPDF_PAGE page = LoadPage(0);
+  ASSERT_TRUE(page);
+
+  ASSERT_FALSE(FORM_OnKeyDown(form_handle(), page, FWL_VKEY_Tab,
+                              FWL_EVENTFLAG_ControlKey));
+
+  ASSERT_FALSE(
+      FORM_OnKeyDown(form_handle(), page, FWL_VKEY_Tab, FWL_EVENTFLAG_AltKey));
+
+  ASSERT_FALSE(
+      FORM_OnKeyDown(form_handle(), page, FWL_VKEY_Tab,
+                     (FWL_EVENTFLAG_ControlKey | FWL_EVENTFLAG_ShiftKey)));
+
+  ASSERT_FALSE(FORM_OnKeyDown(form_handle(), page, FWL_VKEY_Tab,
+                              (FWL_EVENTFLAG_AltKey | FWL_EVENTFLAG_ShiftKey)));
+
+  UnloadPage(page);
+}
+
+#ifdef PDF_ENABLE_XFA
+TEST_F(FPDFFormFillEmbedderTest, XFAFormFillFirstTab) {
+  EXPECT_TRUE(OpenDocument("xfa/email_recommended.pdf"));
+  FPDF_PAGE page = LoadPage(0);
+  ASSERT_TRUE(page);
+
+  // Invoking first tab on the page.
+  ASSERT_TRUE(FORM_OnKeyDown(form_handle(), page, FWL_VKEY_Tab, 0));
+
+  UnloadPage(page);
+}
+
+TEST_F(FPDFFormFillEmbedderTest, XFAFormFillFirstShiftTab) {
+  EXPECT_TRUE(OpenDocument("xfa/email_recommended.pdf"));
+  FPDF_PAGE page = LoadPage(0);
+  ASSERT_TRUE(page);
+
+  // Invoking first shift-tab on the page.
+  ASSERT_TRUE(FORM_OnKeyDown(form_handle(), page, FWL_VKEY_Tab,
+                             FWL_EVENTFLAG_ShiftKey));
+
+  UnloadPage(page);
+}
+
+TEST_F(FPDFFormFillEmbedderTest, XFAFormFillContinuousTab) {
+  EXPECT_TRUE(OpenDocument("xfa/email_recommended.pdf"));
+  FPDF_PAGE page = LoadPage(0);
+  ASSERT_TRUE(page);
+
+  // Invoking first tab on the page.
+  ASSERT_TRUE(FORM_OnKeyDown(form_handle(), page, FWL_VKEY_Tab, 0));
+
+  // Subsequent tabs should move focus over annotations.
+  for (size_t i = 0; i < 9; ++i)
+    ASSERT_TRUE(FORM_OnKeyDown(form_handle(), page, FWL_VKEY_Tab, 0));
+
+  // Tab should not be handled as the last annotation of the page is in focus.
+  ASSERT_FALSE(FORM_OnKeyDown(form_handle(), page, FWL_VKEY_Tab, 0));
+
+  UnloadPage(page);
+}
+
+TEST_F(FPDFFormFillEmbedderTest, XFAFormFillContinuousShiftTab) {
+  EXPECT_TRUE(OpenDocument("xfa/email_recommended.pdf"));
+  FPDF_PAGE page = LoadPage(0);
+  ASSERT_TRUE(page);
+
+  // Invoking first shift-tab on the page.
+  ASSERT_TRUE(FORM_OnKeyDown(form_handle(), page, FWL_VKEY_Tab,
+                             FWL_EVENTFLAG_ShiftKey));
+
+  // Subsequent shift-tabs should move focus over annotations.
+  for (size_t i = 0; i < 9; ++i) {
+    ASSERT_TRUE(FORM_OnKeyDown(form_handle(), page, FWL_VKEY_Tab,
+                               FWL_EVENTFLAG_ShiftKey));
+  }
+
+  // Shift-tab should not be handled as the first annotation of the page is in
+  // focus.
+  ASSERT_FALSE(FORM_OnKeyDown(form_handle(), page, FWL_VKEY_Tab,
+                              FWL_EVENTFLAG_ShiftKey));
+
+  UnloadPage(page);
+}
+#endif  // PDF_ENABLE_XFA
+
 class DoURIActionBlockedDelegate final : public EmbedderTest::Delegate {
  public:
   void DoURIAction(FPDF_BYTESTRING uri) override {
diff --git a/fpdfsdk/fpdfxfa/cpdfxfa_page.cpp b/fpdfsdk/fpdfxfa/cpdfxfa_page.cpp
index 9797429..d9868ab 100644
--- a/fpdfsdk/fpdfxfa/cpdfxfa_page.cpp
+++ b/fpdfsdk/fpdfxfa/cpdfxfa_page.cpp
@@ -196,12 +196,26 @@
 
   CXFA_FFWidget* hNextFocus =
       bNext ? pWidgetIterator->MoveToNext() : pWidgetIterator->MoveToPrevious();
-  if (!hNextFocus && pSDKAnnot)
-    hNextFocus = pWidgetIterator->MoveToFirst();
+  if (!hNextFocus)
+    return nullptr;
 
   return pPageView->GetAnnotByXFAWidget(hNextFocus);
 }
 
+CPDFSDK_Annot* CPDFXFA_Page::GetFirstOrLastXFAAnnot(CPDFSDK_PageView* page_view,
+                                                    bool last) const {
+  CXFA_FFPageView* xfa_page_view = GetXFAPageView();
+  if (!xfa_page_view)
+    return nullptr;
+  std::unique_ptr<IXFA_WidgetIterator> it =
+      xfa_page_view->CreateTraverseWidgetIterator(XFA_WidgetStatus_Visible |
+                                                  XFA_WidgetStatus_Viewable |
+                                                  XFA_WidgetStatus_Focused);
+
+  return page_view->GetAnnotByXFAWidget(last ? it->MoveToLast()
+                                             : it->MoveToFirst());
+}
+
 int CPDFXFA_Page::HasFormFieldAtPoint(const CFX_PointF& point) const {
   CXFA_FFPageView* pPageView = GetXFAPageView();
   if (!pPageView)
diff --git a/fpdfsdk/fpdfxfa/cpdfxfa_page.h b/fpdfsdk/fpdfxfa/cpdfxfa_page.h
index 73d5421..c121bab 100644
--- a/fpdfsdk/fpdfxfa/cpdfxfa_page.h
+++ b/fpdfsdk/fpdfxfa/cpdfxfa_page.h
@@ -19,6 +19,7 @@
 class CPDF_Dictionary;
 class CPDF_Document;
 class CPDFSDK_Annot;
+class CPDFSDK_PageView;
 class CXFA_FFPageView;
 
 class CPDFXFA_Page final : public IPDF_Page {
@@ -48,6 +49,8 @@
   void SetXFAPageViewIndex(int index) { m_iPageIndex = index; }
   CXFA_FFPageView* GetXFAPageView() const;
   CPDFSDK_Annot* GetNextXFAAnnot(CPDFSDK_Annot* pSDKAnnot, bool bNext);
+  CPDFSDK_Annot* GetFirstOrLastXFAAnnot(CPDFSDK_PageView* page_view,
+                                        bool last) const;
   int HasFormFieldAtPoint(const CFX_PointF& point) const;
   void DrawFocusAnnot(CFX_RenderDevice* pDevice,
                       CPDFSDK_Annot* pAnnot,