diff --git a/frontend/src/components/PasteImportModal.tsx b/frontend/src/components/PasteImportModal.tsx
index 53b40db..c6547e3 100644
--- a/frontend/src/components/PasteImportModal.tsx
+++ b/frontend/src/components/PasteImportModal.tsx
@@ -1,6 +1,10 @@
 import { useState } from 'react';
 import { ClipboardPaste, CheckCircle, AlertTriangle } from 'lucide-react';
+import { toast } from 'sonner';
+
 import api, { type ImportResult } from '@/lib/api';
+import { formatAmount } from '@/lib/format';
+import { formatShortDate } from '@/lib/dates';
 import { Button } from '@/components/ui/button';
 import { Label } from '@/components/ui/label';
 import { Textarea } from '@/components/ui/textarea';
@@ -39,8 +43,40 @@ export default function PasteImportModal({ onClose, onImported }: Props) {
       const { data } = await api.post<ImportResult>('/import/paste', { text, bank, source });
       setResult(data);
       if (data.imported > 0) onImported();
-    } catch (err) {
-      console.error(err);
+    } catch {
+      toast.error('No se pudo importar - revisa el formato');
+    } finally {
+      setImporting(false);
+    }
+  };
+
+  // Re-import ONLY the skipped lines with the dedup check disabled, so rows
+  // that imported on the first pass are never duplicated.
+  const handleImportDuplicates = async () => {
+    if (!result || result.skipped.length === 0) return;
+    const lines = text.trim().split('\n');
+    const dupText = result.skipped
+      .map((s) => lines[s.line - 1])
+      .filter(Boolean)
+      .join('\n');
+    setImporting(true);
+    try {
+      const { data } = await api.post<ImportResult>('/import/paste', {
+        text: dupText,
+        bank,
+        source,
+        allow_duplicates: true,
+      });
+      toast.success(`${data.imported} duplicado(s) importados`);
+      setResult({
+        ...result,
+        imported: result.imported + data.imported,
+        skipped: [],
+        duplicates: 0,
+      });
+      onImported();
+    } catch {
+      toast.error('No se pudieron importar los duplicados');
     } finally {
       setImporting(false);
     }
@@ -134,6 +170,39 @@ export default function PasteImportModal({ onClose, onImported }: Props) {
               </Alert>
             )}
 
+            {result.skipped.length > 0 && (
+              <div className="rounded-lg border border-amber-500/40 bg-amber-500/5 p-3 space-y-2">
+                <p className="text-sm font-medium">
+                  {result.skipped.length} duplicado(s) omitido(s)
+                </p>
+                <ul className="text-xs max-h-40 overflow-y-auto space-y-1.5">
+                  {result.skipped.map((s) => (
+                    <li key={`${s.line}-${s.existing_id}`} className="space-y-0.5">
+                      <span className="font-mono">
+                        {s.merchant} · {formatShortDate(s.date)} ·{' '}
+                        {formatAmount(s.amount, s.currency)}
+                      </span>
+                      <span className="block text-muted-foreground">
+                        coincide con #{s.existing_id}: {s.existing_merchant} del{' '}
+                        {formatShortDate(s.existing_date)} ({s.existing_source})
+                      </span>
+                    </li>
+                  ))}
+                </ul>
+                <Button
+                  variant="outline"
+                  size="sm"
+                  className="w-full"
+                  onClick={handleImportDuplicates}
+                  disabled={importing}
+                >
+                  {importing
+                    ? 'Importando...'
+                    : 'Importar duplicados de todos modos'}
+                </Button>
+              </div>
+            )}
+
             <Button onClick={onClose} className="w-full">
               Done
             </Button>
diff --git a/frontend/src/components/TransactionList.tsx b/frontend/src/components/TransactionList.tsx
index e073cc3..73c62c0 100644
--- a/frontend/src/components/TransactionList.tsx
+++ b/frontend/src/components/TransactionList.tsx
@@ -13,13 +13,22 @@ import {
 
 import { toast } from 'sonner';
 
-import api, { type Transaction } from '@/lib/api';
+import { useQuery } from '@tanstack/react-query';
+
+import api, { type Category, type Transaction } from '@/lib/api';
 import TransactionModal from './TransactionModal';
 import ConfirmDialog from './ConfirmDialog';
 import { Button } from '@/components/ui/button';
 import { Input } from '@/components/ui/input';
 import { Card, CardContent } from '@/components/ui/card';
 import { DataTable } from '@/components/ui/data-table';
+import {
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue,
+} from '@/components/ui/select';
 import { getTransactionColumns } from '@/components/transactions/transaction-columns';
 import { formatAmount } from '@/lib/format';
 import { cn } from '@/lib/utils';
@@ -58,6 +67,40 @@ export default function TransactionList({
   const [deleteId, setDeleteId] = useState<number | null>(null);
   const [pendingDeletes, setPendingDeletes] = useState<Set<number>>(new Set());
   const deleteTimers = useRef<Map<number, ReturnType<typeof setTimeout>>>(new Map());
+  const [selected, setSelected] = useState<Set<number>>(new Set());
+  const [bulkConfirm, setBulkConfirm] = useState(false);
+  const [bulkBusy, setBulkBusy] = useState(false);
+
+  const categoriesQ = useQuery({
+    queryKey: ['categories'],
+    queryFn: ({ signal }) =>
+      api.get<Category[]>('/categories/', { signal }).then((r) =>
+        [...r.data].sort((a, b) => a.name.localeCompare(b.name)),
+      ),
+    enabled: selected.size > 0,
+  });
+
+  const clearSelection = () => setSelected(new Set());
+
+  const runBulk = async (
+    payload: Record<string, unknown>,
+    success: string,
+  ) => {
+    setBulkBusy(true);
+    try {
+      const { data } = await api.post<{ affected: number }>(
+        '/transactions/bulk',
+        { ids: [...selected], ...payload },
+      );
+      toast.success(`${success} (${data.affected})`);
+      clearSelection();
+      onRefresh();
+    } catch {
+      toast.error('No se pudo aplicar la acción masiva');
+    } finally {
+      setBulkBusy(false);
+    }
+  };
 
   const handleEdit = (tx: Transaction) => {
     setEditing(tx);
@@ -111,9 +154,35 @@ export default function TransactionList({
     );
   };
 
+  const allSelected =
+    transactions.length > 0 && transactions.every((t) => selected.has(t.id));
+
   const columns = useMemo(
-    () => getTransactionColumns({ showCategory, showSourceIcon, onEdit: handleEdit, onDelete: (id) => setDeleteId(id), onToggleDeferred }),
-    [showCategory, showSourceIcon, onToggleDeferred],
+    () =>
+      getTransactionColumns({
+        showCategory,
+        showSourceIcon,
+        onEdit: handleEdit,
+        onDelete: (id) => setDeleteId(id),
+        onToggleDeferred,
+        selection: {
+          selected,
+          allSelected,
+          onToggle: (id) =>
+            setSelected((prev) => {
+              const next = new Set(prev);
+              if (next.has(id)) next.delete(id);
+              else next.add(id);
+              return next;
+            }),
+          onToggleAll: () =>
+            setSelected(
+              allSelected ? new Set() : new Set(transactions.map((t) => t.id)),
+            ),
+        },
+      }),
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+    [showCategory, showSourceIcon, onToggleDeferred, selected, allSelected, transactions],
   );
 
   const visibleTransactions = pendingDeletes.size
@@ -140,6 +209,84 @@ export default function TransactionList({
         </Button>
       </div>
 
+      {/* Bulk action bar */}
+      {selected.size > 0 && (
+        <div className="hidden md:flex items-center gap-2 rounded-lg border bg-muted/40 px-3 py-2">
+          <span className="text-sm font-medium">
+            {selected.size} seleccionada{selected.size === 1 ? '' : 's'}
+          </span>
+          <div className="ml-auto flex items-center gap-2">
+            <Select
+              onValueChange={(v) => {
+                if (!v) return;
+                void runBulk(
+                  {
+                    action: 'set_category',
+                    category_id: v === '__none__' ? null : Number(v),
+                  },
+                  'Categoría aplicada',
+                );
+              }}
+            >
+              <SelectTrigger className="h-8 w-44" disabled={bulkBusy}>
+                <SelectValue placeholder="Asignar categoría…" />
+              </SelectTrigger>
+              <SelectContent>
+                <SelectItem value="__none__">Sin categoría</SelectItem>
+                {(categoriesQ.data ?? []).map((c) => (
+                  <SelectItem key={c.id} value={String(c.id)}>
+                    {c.name}
+                  </SelectItem>
+                ))}
+              </SelectContent>
+            </Select>
+            {onToggleDeferred && (
+              <>
+                <Button
+                  variant="outline"
+                  size="sm"
+                  disabled={bulkBusy}
+                  onClick={() =>
+                    void runBulk(
+                      { action: 'set_deferred', deferred: true },
+                      'Transacciones diferidas',
+                    )
+                  }
+                >
+                  Diferir
+                </Button>
+                <Button
+                  variant="outline"
+                  size="sm"
+                  disabled={bulkBusy}
+                  onClick={() =>
+                    void runBulk(
+                      { action: 'set_deferred', deferred: false },
+                      'Diferidas restauradas',
+                    )
+                  }
+                >
+                  Restaurar
+                </Button>
+              </>
+            )}
+            <Button
+              variant="outline"
+              size="sm"
+              className="text-destructive hover:text-destructive"
+              disabled={bulkBusy}
+              onClick={() => setBulkConfirm(true)}
+            >
+              <Trash2 className="w-4 h-4 mr-1" aria-hidden="true" />
+              Eliminar
+            </Button>
+            <Button variant="ghost" size="sm" onClick={clearSelection}>
+              Cancelar
+            </Button>
+          </div>
+        </div>
+      )}
+
       {/* Mobile list */}
       <Card className="md:hidden">
         <CardContent className="p-0 divide-y divide-border">
@@ -149,7 +296,7 @@ export default function TransactionList({
               {emptyMessage}
             </div>
           ) : (
-            transactions.map((tx) => (
+            visibleTransactions.map((tx) => (
               <div key={tx.id} className="flex items-center gap-3 px-4 py-3">
                 <div
                   className={cn(
@@ -177,7 +324,7 @@ export default function TransactionList({
                     )}
                   </div>
                   <p className="text-xs text-muted-foreground">
-                    {new Date(tx.date).toLocaleDateString('en-US', { month: 'short', day: 'numeric' })}
+                    {new Date(tx.date).toLocaleDateString('es-CR', { month: 'short', day: 'numeric' })}
                     {showCategory && tx.category && (
                       <span className="ml-1.5 text-muted-foreground/60">{tx.category.name}</span>
                     )}
@@ -250,6 +397,20 @@ export default function TransactionList({
         />
       )}
 
+      {bulkConfirm && (
+        <ConfirmDialog
+          title={`Eliminar ${selected.size} transacciones`}
+          message="Esta acción no se puede deshacer."
+          confirmLabel="Eliminar todas"
+          loading={bulkBusy}
+          onConfirm={async () => {
+            await runBulk({ action: 'delete' }, 'Transacciones eliminadas');
+            setBulkConfirm(false);
+          }}
+          onCancel={() => setBulkConfirm(false)}
+        />
+      )}
+
       {deleteId !== null && (
         <ConfirmDialog
           title="Delete Transaction"
diff --git a/frontend/src/components/transactions/transaction-columns.tsx b/frontend/src/components/transactions/transaction-columns.tsx
index 0efa029..1e04a7c 100644
--- a/frontend/src/components/transactions/transaction-columns.tsx
+++ b/frontend/src/components/transactions/transaction-columns.tsx
@@ -8,12 +8,20 @@ import { Button } from '@/components/ui/button';
 import { Badge } from '@/components/ui/badge';
 import { DataTableColumnHeader } from '@/components/ui/data-table-column-header';
 
+export interface RowSelection {
+  selected: Set<number>;
+  allSelected: boolean;
+  onToggle: (id: number) => void;
+  onToggleAll: () => void;
+}
+
 interface TransactionColumnOptions {
   showCategory: boolean;
   showSourceIcon?: boolean;
   onEdit: (tx: Transaction) => void;
   onDelete: (txId: number) => void;
   onToggleDeferred?: (tx: Transaction) => void;
+  selection?: RowSelection;
 }
 
 export function getTransactionColumns({
@@ -22,14 +30,43 @@ export function getTransactionColumns({
   onEdit,
   onDelete,
   onToggleDeferred,
+  selection,
 }: TransactionColumnOptions): ColumnDef<Transaction, unknown>[] {
-  const columns: ColumnDef<Transaction, unknown>[] = [
+  const columns: ColumnDef<Transaction, unknown>[] = [];
+
+  if (selection) {
+    columns.push({
+      id: 'select',
+      size: 36,
+      enableSorting: false,
+      header: () => (
+        <input
+          type="checkbox"
+          className="accent-primary w-4 h-4 cursor-pointer align-middle"
+          aria-label="Seleccionar todas las transacciones"
+          checked={selection.allSelected}
+          onChange={selection.onToggleAll}
+        />
+      ),
+      cell: ({ row }) => (
+        <input
+          type="checkbox"
+          className="accent-primary w-4 h-4 cursor-pointer align-middle"
+          aria-label={`Seleccionar ${row.original.merchant}`}
+          checked={selection.selected.has(row.original.id)}
+          onChange={() => selection.onToggle(row.original.id)}
+        />
+      ),
+    });
+  }
+
+  columns.push(
     {
       accessorKey: 'date',
       header: ({ column }) => <DataTableColumnHeader column={column} title="Date" />,
       cell: ({ row }) => (
         <span className="font-mono text-muted-foreground text-xs whitespace-nowrap">
-          {new Date(row.original.date).toLocaleDateString('en-US', {
+          {new Date(row.original.date).toLocaleDateString('es-CR', {
             month: 'short',
             day: 'numeric',
             year: 'numeric',
@@ -74,7 +111,7 @@ export function getTransactionColumns({
         );
       },
     },
-  ];
+  );
 
   if (showCategory) {
     columns.push({
diff --git a/frontend/src/lib/api.ts b/frontend/src/lib/api.ts
index 272e54d..3661185 100644
--- a/frontend/src/lib/api.ts
+++ b/frontend/src/lib/api.ts
@@ -143,10 +143,24 @@ export interface Category {
   auto_match_patterns: string | null;
 }
 
+export interface SkippedDuplicate {
+  line: number;
+  merchant: string;
+  date: string;
+  amount: number;
+  currency: string;
+  existing_id: number;
+  existing_merchant: string;
+  existing_date: string;
+  existing_amount: number;
+  existing_source: string;
+}
+
 export interface ImportResult {
   imported: number;
   duplicates: number;
   errors: string[];
+  skipped: SkippedDuplicate[];
 }
 
 export interface Transaction {