diff --git a/frontend/src/energy/CostView.test.tsx b/frontend/src/energy/CostView.test.tsx
index bb5eb36..2cede7a 100644
--- a/frontend/src/energy/CostView.test.tsx
+++ b/frontend/src/energy/CostView.test.tsx
@@ -114,6 +114,12 @@ const THERMAL_DEGRADED_CROSS_EPOCH = {
 const ACTIVE_HEATING_METER = { id: 10, commodity: 'heating', ended_at: null }
 const ACTIVE_HOT_WATER_METER = { id: 11, commodity: 'hot_water', ended_at: null }
 const ENDED_HEATING_METER = { id: 9, commodity: 'heating', ended_at: '2026-06-01T00:00:00Z' }
+const CLOSED_THERMAL_RANGE = {
+  startDate: '2020-01-01',
+  endDate: '2020-01-02',
+  start: '2020-01-01T00:00:00.000Z',
+  end: '2020-01-02T00:00:00.000Z',
+}
 
 // ---------------------------------------------------------------------------
 // Import component
@@ -297,13 +303,20 @@ describe('CostView', () => {
     expect(screen.getByTestId('thermal-fixed-breakdown')).toHaveTextContent('summary only')
     expect(screen.getAllByText(/Fixed subtotal|All-in total/)).toHaveLength(2)
     expect(screen.getByTestId('thermal-costs-table')).not.toHaveTextContent('Fixed')
+    await user.click(screen.getByTestId('thermal-cost-range-control'))
+    await user.click(screen.getByText('Custom'))
+    expect(screen.getByTestId('thermal-recompute-button')).toBeDisabled()
+    await user.type(screen.getByTestId('thermal-cost-custom-start'), CLOSED_THERMAL_RANGE.startDate)
+    await user.type(screen.getByTestId('thermal-cost-custom-end'), CLOSED_THERMAL_RANGE.endDate)
+    await waitFor(() => expect(screen.getByTestId('thermal-recompute-button')).toBeEnabled())
     await user.click(screen.getByTestId('thermal-recompute-button'))
     expect(screen.getByTestId('thermal-recompute-confirm-modal')).toHaveTextContent('closed 15-minute')
     await user.click(screen.getByTestId('thermal-recompute-confirm'))
-    await waitFor(() => expect(mockPost).toHaveBeenCalledWith('/api/energy/meter-costs/recompute', expect.any(Object)))
-    const options = mockPost.mock.calls.find(([path]) => path === '/api/energy/meter-costs/recompute')?.[1] as { params: { query: { end: string } } }
-    expect(new Date(options.params.query.end).getTime()).toBeLessThanOrEqual(Date.now())
-    expect(new Date(options.params.query.end).getUTCMinutes() % 15).toBe(0)
+    await waitFor(() => expect(mockPost).toHaveBeenCalledWith(
+      '/api/energy/meter-costs/recompute',
+      { params: { query: { scope: 'thermal', start: CLOSED_THERMAL_RANGE.start, end: CLOSED_THERMAL_RANGE.end } } },
+    ))
+    expect(new Date(CLOSED_THERMAL_RANGE.end).getUTCMinutes() % 15).toBe(0)
   })
 
   it('keeps the thermal confirmation cancellable and surfaces a 422 recompute failure', async () => {
@@ -318,9 +331,18 @@ describe('CostView', () => {
     renderWithProviders(<CostView />)
     await user.click(screen.getByTestId('costs-scope-selector')); await user.click(screen.getByText('Thermal'))
     await waitFor(() => expect(screen.getByTestId('thermal-recompute-button')).toBeInTheDocument())
+    await user.click(screen.getByTestId('thermal-cost-range-control')); await user.click(screen.getByText('Custom'))
+    expect(screen.getByTestId('thermal-recompute-button')).toBeDisabled()
+    await user.type(screen.getByTestId('thermal-cost-custom-start'), CLOSED_THERMAL_RANGE.startDate)
+    await user.type(screen.getByTestId('thermal-cost-custom-end'), CLOSED_THERMAL_RANGE.endDate)
+    await waitFor(() => expect(screen.getByTestId('thermal-recompute-button')).toBeEnabled())
     await user.click(screen.getByTestId('thermal-recompute-button')); await user.click(screen.getByTestId('thermal-recompute-cancel'))
     expect(screen.queryByTestId('thermal-recompute-confirm-modal')).not.toBeInTheDocument()
     await user.click(screen.getByTestId('thermal-recompute-button')); await user.click(screen.getByTestId('thermal-recompute-confirm'))
+    await waitFor(() => expect(mockPost).toHaveBeenCalledWith(
+      '/api/energy/meter-costs/recompute',
+      { params: { query: { scope: 'thermal', start: CLOSED_THERMAL_RANGE.start, end: CLOSED_THERMAL_RANGE.end } } },
+    ))
     await waitFor(() => expect(screen.getByTestId('thermal-recompute-error')).toBeInTheDocument())
   })