diff --git a/frontend/.claude/tdd-guard/data/test.json b/frontend/.claude/tdd-guard/data/test.json
index bf2a3fc..a9ae213 100644
--- a/frontend/.claude/tdd-guard/data/test.json
+++ b/frontend/.claude/tdd-guard/data/test.json
@@ -19,8 +19,8 @@
           "state": "passed"
         },
         {
-          "name": "should display subtype chips",
-          "fullName": "MaintenanceScheduleReviewScreen Rendering should display subtype chips",
+          "name": "should display subtypes in SubtypeCheckboxGroup",
+          "fullName": "MaintenanceScheduleReviewScreen Rendering should display subtypes in SubtypeCheckboxGroup",
           "state": "passed"
         },
         {
@@ -68,6 +68,26 @@
           "fullName": "MaintenanceScheduleReviewScreen Editing should update item data via inline editing",
           "state": "passed"
         },
+        {
+          "name": "should disable create button when selected item has empty subtypes",
+          "fullName": "MaintenanceScheduleReviewScreen Subtype validation should disable create button when selected item has empty subtypes",
+          "state": "passed"
+        },
+        {
+          "name": "should enable create button after deselecting item with empty subtypes",
+          "fullName": "MaintenanceScheduleReviewScreen Subtype validation should enable create button after deselecting item with empty subtypes",
+          "state": "passed"
+        },
+        {
+          "name": "should show warning alert for items missing subtypes",
+          "fullName": "MaintenanceScheduleReviewScreen Subtype validation should show warning alert for items missing subtypes",
+          "state": "passed"
+        },
+        {
+          "name": "should hide warning alert after deselecting items with empty subtypes",
+          "fullName": "MaintenanceScheduleReviewScreen Subtype validation should hide warning alert after deselecting items with empty subtypes",
+          "state": "passed"
+        },
         {
           "name": "should render in fullscreen mode on mobile viewports",
           "fullName": "MaintenanceScheduleReviewScreen Responsive layout should render in fullscreen mode on mobile viewports",
diff --git a/frontend/src/features/maintenance/components/MaintenanceScheduleReviewScreen.test.tsx b/frontend/src/features/maintenance/components/MaintenanceScheduleReviewScreen.test.tsx
index 16e9ea8..534e007 100644
--- a/frontend/src/features/maintenance/components/MaintenanceScheduleReviewScreen.test.tsx
+++ b/frontend/src/features/maintenance/components/MaintenanceScheduleReviewScreen.test.tsx
@@ -33,6 +33,21 @@ jest.mock('../hooks/useCreateSchedulesFromExtraction', () => ({
   }),
 }));
 
+// Track SubtypeCheckboxGroup onChange callbacks per instance
+const subtypeOnChangeCallbacks: Array<(subtypes: string[]) => void> = [];
+jest.mock('./SubtypeCheckboxGroup', () => ({
+  SubtypeCheckboxGroup: ({ selected, onChange }: { category: string; selected: string[]; onChange: (subtypes: string[]) => void }) => {
+    subtypeOnChangeCallbacks.push(onChange);
+    return (
+      <div data-testid="subtype-checkbox-group">
+        {selected.map((s: string) => (
+          <span key={s} data-testid="subtype-chip">{s}</span>
+        ))}
+      </div>
+    );
+  },
+}));
+
 const sampleItems: MaintenanceScheduleItem[] = [
   {
     service: 'Engine Oil Change',
@@ -60,6 +75,18 @@ const sampleItems: MaintenanceScheduleItem[] = [
   },
 ];
 
+const sampleItemsWithEmpty: MaintenanceScheduleItem[] = [
+  ...sampleItems,
+  {
+    service: 'Brake Fluid',
+    intervalMiles: 30000,
+    intervalMonths: 24,
+    details: null,
+    confidence: 0.65,
+    subtypes: [],
+  },
+];
+
 describe('MaintenanceScheduleReviewScreen', () => {
   const defaultProps = {
     open: true,
@@ -72,6 +99,7 @@ describe('MaintenanceScheduleReviewScreen', () => {
   beforeEach(() => {
     jest.clearAllMocks();
     mockMutateAsync.mockResolvedValue([]);
+    subtypeOnChangeCallbacks.length = 0;
   });
 
   describe('Rendering', () => {
@@ -109,9 +137,12 @@ describe('MaintenanceScheduleReviewScreen', () => {
       expect(screen.getByText('Use 0W-20 full synthetic oil')).toBeInTheDocument();
     });
 
-    it('should display subtype chips', () => {
+    it('should display subtypes in SubtypeCheckboxGroup', () => {
       render(<MaintenanceScheduleReviewScreen {...defaultProps} />);
 
+      const groups = screen.getAllByTestId('subtype-checkbox-group');
+      expect(groups).toHaveLength(3);
+
       expect(screen.getByText('Engine Oil')).toBeInTheDocument();
       expect(screen.getByText('Tires')).toBeInTheDocument();
       expect(screen.getByText('Cabin Air Filter / Purifier')).toBeInTheDocument();
@@ -273,6 +304,43 @@ describe('MaintenanceScheduleReviewScreen', () => {
     });
   });
 
+  describe('Subtype validation', () => {
+    it('should disable create button when selected item has empty subtypes', () => {
+      render(<MaintenanceScheduleReviewScreen {...defaultProps} items={sampleItemsWithEmpty} />);
+
+      // All 4 items selected, but Brake Fluid has no subtypes
+      const createButton = screen.getByRole('button', { name: /create/i });
+      expect(createButton).toBeDisabled();
+    });
+
+    it('should enable create button after deselecting item with empty subtypes', () => {
+      render(<MaintenanceScheduleReviewScreen {...defaultProps} items={sampleItemsWithEmpty} />);
+
+      // Deselect the 4th item (Brake Fluid with empty subtypes)
+      const checkboxes = screen.getAllByRole('checkbox');
+      fireEvent.click(checkboxes[3]);
+
+      const createButton = screen.getByRole('button', { name: /create 3 schedules/i });
+      expect(createButton).not.toBeDisabled();
+    });
+
+    it('should show warning alert for items missing subtypes', () => {
+      render(<MaintenanceScheduleReviewScreen {...defaultProps} items={sampleItemsWithEmpty} />);
+
+      expect(screen.getByText(/missing subtypes/)).toBeInTheDocument();
+    });
+
+    it('should hide warning alert after deselecting items with empty subtypes', () => {
+      render(<MaintenanceScheduleReviewScreen {...defaultProps} items={sampleItemsWithEmpty} />);
+
+      // Deselect the Brake Fluid item
+      const checkboxes = screen.getAllByRole('checkbox');
+      fireEvent.click(checkboxes[3]);
+
+      expect(screen.queryByText(/missing subtypes/)).not.toBeInTheDocument();
+    });
+  });
+
   describe('Responsive layout', () => {
     afterEach(() => {
       // Reset matchMedia after each test
diff --git a/frontend/src/features/maintenance/components/MaintenanceScheduleReviewScreen.tsx b/frontend/src/features/maintenance/components/MaintenanceScheduleReviewScreen.tsx
index 259dc60..289a572 100644
--- a/frontend/src/features/maintenance/components/MaintenanceScheduleReviewScreen.tsx
+++ b/frontend/src/features/maintenance/components/MaintenanceScheduleReviewScreen.tsx
@@ -17,7 +17,7 @@ import {
   IconButton,
   Alert,
   CircularProgress,
-  Chip,
+  Tooltip,
   useTheme,
   useMediaQuery,
 } from '@mui/material';
@@ -26,8 +26,11 @@ import CheckIcon from '@mui/icons-material/Check';
 import CloseIcon from '@mui/icons-material/Close';
 import SelectAllIcon from '@mui/icons-material/SelectAll';
 import DeselectIcon from '@mui/icons-material/Deselect';
+import WarningAmberIcon from '@mui/icons-material/WarningAmber';
 import type { MaintenanceScheduleItem } from '../../documents/hooks/useManualExtraction';
 import { useCreateSchedulesFromExtraction } from '../hooks/useCreateSchedulesFromExtraction';
+import { SubtypeCheckboxGroup } from './SubtypeCheckboxGroup';
+import { getSubtypesForCategory } from '../types/maintenance.types';
 
 export interface MaintenanceScheduleReviewScreenProps {
   open: boolean;
@@ -176,12 +179,18 @@ export const MaintenanceScheduleReviewScreen: React.FC<MaintenanceScheduleReview
   const isMobile = useMediaQuery(theme.breakpoints.down('sm'));
   const createMutation = useCreateSchedulesFromExtraction();
 
+  const validRoutineSubtypes = getSubtypesForCategory('routine_maintenance');
   const [editableItems, setEditableItems] = useState<EditableItem[]>(() =>
-    items.map((item) => ({ ...item, selected: true }))
+    items.map((item) => ({
+      ...item,
+      subtypes: item.subtypes.filter((st) => validRoutineSubtypes.includes(st)),
+      selected: true,
+    }))
   );
   const [createError, setCreateError] = useState<string | null>(null);
 
   const selectedCount = editableItems.filter((i) => i.selected).length;
+  const hasInvalidSubtypes = editableItems.some((i) => i.selected && i.subtypes.length === 0);
 
   const handleToggle = useCallback((index: number) => {
     setEditableItems((prev) =>
@@ -203,6 +212,12 @@ export const MaintenanceScheduleReviewScreen: React.FC<MaintenanceScheduleReview
     );
   }, []);
 
+  const handleSubtypesChange = useCallback((index: number, subtypes: string[]) => {
+    setEditableItems((prev) =>
+      prev.map((item, i) => (i === index ? { ...item, subtypes } : item))
+    );
+  }, []);
+
   const handleCreate = async () => {
     setCreateError(null);
     const selectedItems = editableItems.filter((i) => i.selected);
@@ -334,18 +349,34 @@ export const MaintenanceScheduleReviewScreen: React.FC<MaintenanceScheduleReview
                       </Typography>
                     )}
 
-                    {item.subtypes.length > 0 && (
-                      <Box sx={{ display: 'flex', flexWrap: 'wrap', gap: 0.5, mt: 0.5 }}>
-                        {item.subtypes.map((subtype) => (
-                          <Chip key={subtype} label={subtype} size="small" variant="outlined" />
-                        ))}
+                    <Box sx={{ mt: 1 }}>
+                      <Box sx={{ display: 'flex', alignItems: 'center', gap: 1, mb: 0.5 }}>
+                        <Typography variant="caption" color="text.secondary">
+                          Subtypes:
+                        </Typography>
+                        {item.subtypes.length === 0 && item.selected && (
+                          <Tooltip title="At least one subtype is required">
+                            <WarningAmberIcon color="warning" sx={{ fontSize: 18 }} />
+                          </Tooltip>
+                        )}
                       </Box>
-                    )}
+                      <SubtypeCheckboxGroup
+                        category="routine_maintenance"
+                        selected={item.subtypes}
+                        onChange={(subtypes) => handleSubtypesChange(index, subtypes)}
+                      />
+                    </Box>
                   </Box>
                 </Box>
               ))}
             </Box>
 
+            {hasInvalidSubtypes && (
+              <Alert severity="warning" sx={{ mt: 2 }}>
+                Some selected items are missing subtypes. Please select at least one subtype for each selected item.
+              </Alert>
+            )}
+
             <Typography variant="body2" color="text.secondary" sx={{ mt: 2, textAlign: 'center' }}>
               Tap any field to edit before creating schedules.
             </Typography>
@@ -378,7 +409,7 @@ export const MaintenanceScheduleReviewScreen: React.FC<MaintenanceScheduleReview
             <Button
               variant="contained"
               onClick={handleCreate}
-              disabled={selectedCount === 0 || createMutation.isPending}
+              disabled={selectedCount === 0 || hasInvalidSubtypes || createMutation.isPending}
               startIcon={createMutation.isPending ? <CircularProgress size={16} /> : <CheckIcon />}
               sx={{ minHeight: 44, order: isMobile ? 1 : 2, width: isMobile ? '100%' : 'auto' }}
             >
diff --git a/frontend/src/features/maintenance/hooks/useCreateSchedulesFromExtraction.ts b/frontend/src/features/maintenance/hooks/useCreateSchedulesFromExtraction.ts
index cb3da87..934b057 100644
--- a/frontend/src/features/maintenance/hooks/useCreateSchedulesFromExtraction.ts
+++ b/frontend/src/features/maintenance/hooks/useCreateSchedulesFromExtraction.ts
@@ -20,10 +20,11 @@ export function useCreateSchedulesFromExtraction() {
     mutationFn: async ({ vehicleId, items }) => {
       const results: MaintenanceScheduleResponse[] = [];
       for (const item of items) {
+        if (item.subtypes.length === 0) continue;
         const request: CreateScheduleRequest = {
           vehicleId,
           category: 'routine_maintenance',
-          subtypes: item.subtypes.length > 0 ? item.subtypes : [],
+          subtypes: item.subtypes,
           scheduleType: 'interval',
           intervalMiles: item.intervalMiles ?? undefined,
           intervalMonths: item.intervalMonths ?? undefined,