diff --git a/packages/ag-grid-enterprise/src/agStack/agGroupComponent.ts b/packages/ag-grid-enterprise/src/agStack/agGroupComponent.ts
index 9bd31ae13cb..22edb7d6060 100644
--- a/packages/ag-grid-enterprise/src/agStack/agGroupComponent.ts
+++ b/packages/ag-grid-enterprise/src/agStack/agGroupComponent.ts
@@ -11,7 +11,9 @@ import {
     AgComponentStub,
     RefPlaceholder,
     _isComponent,
+    _removeAriaExpanded,
     _removeFromParent,
+    _setAriaControls,
     _setAriaExpanded,
     _setAriaRole,
     _setDisplayed,
@@ -412,6 +414,8 @@ export class AgGroupComponent<
         TPropertiesService,
         TComponentSelectorType
     > {
+        const containerId = `ag-${this.getCompId()}-group-container`;
+        this.eContainer.id = containerId;
         const titleBar = this.createManagedBean(
             new DefaultTitleBar<
                 TBeanCollection,
@@ -420,7 +424,7 @@ export class AgGroupComponent<
                 TCommon,
                 TPropertiesService,
                 TComponentSelectorType
-            >(this.params)
+            >(this.params, containerId)
         );
         this.eTitleBar = titleBar;
         titleBar.refreshOnExpand(this.expanded);
@@ -471,26 +475,28 @@ const TITLE_BAR_DISABLED_CLASS = 'ag-disabled-group-title-bar';
 function getDefaultTitleBarTemplate<TBeanCollection, TComponentSelectorType extends string>(
     params: AgGroupComponentParams<TBeanCollection>
 ): AgElementParams<TComponentSelectorType> {
-    const cssIdentifier = params.cssIdentifier ?? 'default';
+    const { cssIdentifier, suppressOpenCloseIcons } = params;
+    const normalisedCssIdentifier = cssIdentifier ?? 'default';
+    const interactiveRole = suppressOpenCloseIcons ? 'group' : 'button';
 
     return {
         tag: 'div',
-        cls: `ag-group-title-bar ag-${cssIdentifier}-group-title-bar ag-unselectable`,
-        role: params.suppressKeyboardNavigation ? 'presentation' : 'group',
+        cls: `ag-group-title-bar ag-${normalisedCssIdentifier}-group-title-bar ag-unselectable`,
+        role: params.suppressKeyboardNavigation ? 'presentation' : interactiveRole,
         children: [
             {
                 tag: 'span',
                 ref: 'eGroupOpenedIcon',
-                cls: `ag-group-title-bar-icon ag-${cssIdentifier}-group-title-bar-icon`,
+                cls: `ag-group-title-bar-icon ag-${normalisedCssIdentifier}-group-title-bar-icon`,
                 role: 'presentation',
             },
             {
                 tag: 'span',
                 ref: 'eGroupClosedIcon',
-                cls: `ag-group-title-bar-icon ag-${cssIdentifier}-group-title-bar-icon`,
+                cls: `ag-group-title-bar-icon ag-${normalisedCssIdentifier}-group-title-bar-icon`,
                 role: 'presentation',
             },
-            { tag: 'span', ref: 'eTitle', cls: `ag-group-title ag-${cssIdentifier}-group-title` },
+            { tag: 'span', ref: 'eTitle', cls: `ag-group-title ag-${normalisedCssIdentifier}-group-title` },
         ],
     };
 }
@@ -513,12 +519,17 @@ class DefaultTitleBar<
     private title: string | undefined;
     private suppressOpenCloseIcons: boolean = false;
     private readonly suppressKeyboardNavigation: boolean = false;
+    private expanded: boolean = true;
+    private disabled: boolean = false;
 
     private readonly eGroupOpenedIcon: HTMLElement = RefPlaceholder;
     private readonly eGroupClosedIcon: HTMLElement = RefPlaceholder;
     private readonly eTitle: HTMLElement = RefPlaceholder;
 
-    constructor(params: AgGroupComponentParams<TBeanCollection> = {}) {
+    constructor(
+        params: AgGroupComponentParams<TBeanCollection> = {},
+        private readonly containerId?: string
+    ) {
         super(getDefaultTitleBarTemplate(params));
 
         const { title, suppressOpenCloseIcons, suppressKeyboardNavigation } = params;
@@ -575,14 +586,39 @@ class DefaultTitleBar<
     }
 
     public refreshOnExpand(expanded: boolean): void {
-        this.refreshAriaStatus(expanded);
+        this.expanded = expanded;
+        this.refreshAriaState();
         this.refreshOpenCloseIcons(expanded);
     }
 
-    private refreshAriaStatus(expanded: boolean): void {
-        if (!this.suppressOpenCloseIcons) {
-            _setAriaExpanded(this.getGui(), expanded);
+    private refreshAriaState(): void {
+        const eGui = this.getGui();
+        const interactive = this.title != null && !this.suppressKeyboardNavigation && !this.disabled;
+        // suppressed open/close icons means the group cannot collapse, so no disclosure button semantics
+        const collapsible = interactive && !this.suppressOpenCloseIcons;
+
+        let role = 'presentation';
+
+        if (collapsible) {
+            role = 'button';
+        } else if (interactive) {
+            role = 'group';
+        }
+
+        _setAriaRole(eGui, role);
+
+        if (interactive) {
+            this.activateTabIndex([eGui]);
+        } else {
+            eGui.removeAttribute('tabindex');
         }
+
+        if (collapsible) {
+            _setAriaExpanded(eGui, this.expanded);
+        } else {
+            _removeAriaExpanded(eGui);
+        }
+        _setAriaControls(eGui, collapsible ? this.containerId : null);
     }
 
     private refreshOpenCloseIcons(expanded: boolean): void {
@@ -616,8 +652,7 @@ class DefaultTitleBar<
             this.title = title;
         }
 
-        const disabled = eGui.classList.contains(TITLE_BAR_DISABLED_CLASS);
-        this.refreshDisabledStyles(disabled);
+        this.refreshAriaState();
 
         return this;
     }
@@ -635,25 +670,15 @@ class DefaultTitleBar<
             this.dispatchExpandChanged(true);
         }
 
+        this.refreshAriaState();
+
         return this;
     }
 
     public refreshDisabledStyles(disabled: boolean) {
-        const eGui = this.getGui();
-        if (disabled) {
-            eGui.classList.add(TITLE_BAR_DISABLED_CLASS);
-            eGui.removeAttribute('tabindex');
-            _setAriaRole(eGui, 'presentation');
-        } else {
-            eGui.classList.remove(TITLE_BAR_DISABLED_CLASS);
-            if (typeof this.title === 'string' && !this.suppressKeyboardNavigation) {
-                this.activateTabIndex([eGui]);
-                _setAriaRole(eGui, 'group');
-            } else {
-                eGui.removeAttribute('tabindex');
-                _setAriaRole(eGui, 'presentation');
-            }
-        }
+        this.disabled = disabled;
+        this.getGui().classList.toggle(TITLE_BAR_DISABLED_CLASS, disabled);
+        this.refreshAriaState();
     }
 }
 
diff --git a/packages/ag-grid-enterprise/src/filterToolPanel/agFiltersToolPanelList.ts b/packages/ag-grid-enterprise/src/filterToolPanel/agFiltersToolPanelList.ts
index fd44731461b..d8d61594225 100644
--- a/packages/ag-grid-enterprise/src/filterToolPanel/agFiltersToolPanelList.ts
+++ b/packages/ag-grid-enterprise/src/filterToolPanel/agFiltersToolPanelList.ts
@@ -41,7 +41,7 @@ export class AgFiltersToolPanelList extends Component<AgFiltersToolPanelListEven
     private onColumnsChangedPending: boolean = false;
 
     constructor() {
-        super({ tag: 'div', cls: 'ag-filter-list-panel' });
+        super({ tag: 'div', cls: 'ag-filter-list-panel', role: 'group' });
     }
 
     public init(params: ToolPanelFiltersCompParams): void {
diff --git a/testing/behavioural/src/charts/format-panel-title-bar-roles.test.ts b/testing/behavioural/src/charts/format-panel-title-bar-roles.test.ts
new file mode 100644
index 00000000000..1031a88521a
--- /dev/null
+++ b/testing/behavioural/src/charts/format-panel-title-bar-roles.test.ts
@@ -0,0 +1,76 @@
+import { waitFor } from '@testing-library/dom';
+import { AgChartsEnterpriseModule } from 'ag-charts-enterprise';
+import { TestGridsManager, canvasPolyfill } from 'ag-test-utils';
+
+import { ClientSideRowModelModule } from 'ag-grid-community';
+import { CellSelectionModule, IntegratedChartsModule } from 'ag-grid-enterprise';
+
+/**
+ * Aria contract of the format panel's group title bars, in its own suite because the sibling
+ * `format-panel-options-*` suites own the option *bindings*, not the panel DOM. The format panel is
+ * the one surface reachable through the public API that renders both title-bar states of the shared
+ * group component: expandable groups (disclosure buttons) and non-collapsible groups, which have
+ * their open/close icons suppressed and must not present as disclosure buttons.
+ */
+describe('chart format panel title bar roles', () => {
+    const gridsManager = new TestGridsManager({
+        modules: [ClientSideRowModelModule, CellSelectionModule, IntegratedChartsModule.with(AgChartsEnterpriseModule)],
+    });
+
+    beforeAll(async () => {
+        await canvasPolyfill.init();
+    });
+    afterAll(() => canvasPolyfill.reset());
+    afterEach(() => gridsManager.reset());
+
+    test('expandable groups are disclosure buttons; non-collapsible groups are plain groups', async () => {
+        const api = await gridsManager.createGridAndWait('grid1', {
+            columnDefs: [
+                { field: 'country', chartDataType: 'category' },
+                { field: 'gold', chartDataType: 'series' },
+            ],
+            rowData: [
+                { country: 'Russia', gold: 3 },
+                { country: 'USA', gold: 4 },
+            ],
+            cellSelection: true,
+            popupParent: document.body,
+        });
+        const chartRef = api.createRangeChart({
+            cellRange: { columns: ['country', 'gold'] },
+            chartType: 'groupedColumn',
+        })!;
+        await chartRef.chart.waitForUpdate();
+
+        api.openChartToolPanel({ chartId: chartRef.chartId, panel: 'format' });
+        await chartRef.chart.waitForUpdate();
+
+        // The format panel builds its groups on the controller's next chartUpdated event, so poll
+        // for the panel DOM rather than assuming it is present once the chart has settled.
+        const topLevel = await waitFor(() => {
+            const titleBar = document.querySelector('.ag-charts-format-top-level-group-title-bar');
+            expect(titleBar).not.toBeNull();
+            return titleBar!;
+        });
+
+        // Top-level accordion groups (Chart, Legend, ...) expand and collapse: disclosure buttons,
+        // announcing their state and wired via aria-controls to the container they show/hide.
+        expect(topLevel?.getAttribute('role')).toBe('button');
+        expect(topLevel?.getAttribute('tabindex')).toBe('0');
+        expect(topLevel?.hasAttribute('aria-expanded')).toBe(true);
+        const controlled = document.getElementById(topLevel?.getAttribute('aria-controls') ?? '');
+        expect(controlled?.classList.contains('ag-group-container')).toBe(true);
+
+        // The Padding sub-group cannot collapse (open/close icons suppressed), so it is a labelled
+        // group with no disclosure state — but still focusable for keyboard navigation.
+        const subLevelBars = Array.from(document.querySelectorAll('.ag-charts-format-sub-level-group-title-bar'));
+        const padding = subLevelBars.find(
+            (bar) => bar.querySelector('.ag-group-title')?.textContent?.trim() === 'Padding'
+        );
+        expect(padding).toBeDefined();
+        expect(padding?.getAttribute('role')).toBe('group');
+        expect(padding?.getAttribute('tabindex')).toBe('0');
+        expect(padding?.hasAttribute('aria-expanded')).toBe(false);
+        expect(padding?.hasAttribute('aria-controls')).toBe(false);
+    });
+});
diff --git a/testing/behavioural/src/filters/filter-behaviour/filters-tool-panel.test.ts b/testing/behavioural/src/filters/filter-behaviour/filters-tool-panel.test.ts
index 9a05f9446e7..50e4d638cfe 100644
--- a/testing/behavioural/src/filters/filter-behaviour/filters-tool-panel.test.ts
+++ b/testing/behavioural/src/filters/filter-behaviour/filters-tool-panel.test.ts
@@ -153,6 +153,48 @@ describe('Filters Tool Panel', () => {
         expect(panel.isGroupExpandedByTitle('Person')).toBe(true);
     });
 
+    test('group title bars are disclosure buttons wired to the container they expand', async () => {
+        const api = await gridsManager.createGridAndWait('grid1', {
+            columnDefs: [
+                {
+                    headerName: 'Person',
+                    children: [
+                        { field: 'name', filter: 'agTextColumnFilter', filterParams: { debounceMs: 0 } },
+                        { field: 'age', filter: 'agNumberColumnFilter', filterParams: { debounceMs: 0 } },
+                    ],
+                },
+            ],
+            rowData: [{ name: 'Alice', age: 30 }],
+            sideBar: FILTERS_SIDEBAR,
+        });
+        const panel = await openFiltersPanel(api);
+
+        // The list container carries the panel's label, which only names it under a role that
+        // permits naming (a bare div's aria-label is ignored).
+        const listPanel = document.querySelector('.ag-filter-list-panel');
+        expect(listPanel?.getAttribute('role')).toBe('group');
+        expect(listPanel?.getAttribute('aria-label')).toMatch(/^Filter List \d+ Filters$/);
+
+        // An expandable group's title bar is a disclosure button: focusable, announcing its state,
+        // and wired via aria-controls to the container it shows/hides.
+        const titleBar = document.querySelector('.ag-filter-toolpanel-group-wrapper .ag-group-title-bar');
+        expect(titleBar?.getAttribute('role')).toBe('button');
+        expect(titleBar?.getAttribute('tabindex')).toBe('0');
+        expect(titleBar?.getAttribute('aria-expanded')).toBe('true');
+
+        const container = document.getElementById(titleBar?.getAttribute('aria-controls') ?? '');
+        expect(container?.classList.contains('ag-group-container')).toBe(true);
+        expect(container?.querySelector('.ag-filter-toolpanel-instance')).not.toBeNull();
+
+        await panel.collapseGroup('Person');
+        expect(titleBar?.getAttribute('aria-expanded')).toBe('false');
+
+        // Space re-expands it, as button semantics promise.
+        titleBar?.dispatchEvent(new KeyboardEvent('keydown', { key: ' ', bubbles: true }));
+        expect(titleBar?.getAttribute('aria-expanded')).toBe('true');
+        expect(panel.isGroupExpandedByTitle('Person')).toBe(true);
+    });
+
     test('column suppressFiltersToolPanel hides the column from the panel but keeps it filterable', async () => {
         const api = await gridsManager.createGridAndWait('grid1', {
             columnDefs: [