diff --git a/src/app/api/shared-transactions/route.ts b/src/app/api/shared-transactions/route.ts
index 52b9ccb..493ae81 100644
--- a/src/app/api/shared-transactions/route.ts
+++ b/src/app/api/shared-transactions/route.ts
@@ -7,7 +7,9 @@ export async function GET(req: NextRequest) {
   if (!user) return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
 
   const tagParam = req.nextUrl.searchParams.get("tag_ids");
-  const tagIds = tagParam ? tagParam.split(",").map(Number).filter(Boolean) : undefined;
-  const transactions = await getSharedTransactions(user.id, tagIds);
+  const rawIds = tagParam ? tagParam.split(",").filter(Boolean) : [];
+  const noTags = rawIds.includes("untagged");
+  const tagIds = rawIds.filter((id) => id !== "untagged").map(Number).filter((n) => !isNaN(n));
+  const transactions = await getSharedTransactions(user.id, tagIds.length ? tagIds : undefined, noTags);
   return NextResponse.json(transactions);
 }
diff --git a/src/app/shared/page.tsx b/src/app/shared/page.tsx
index c377b8d..d1039f3 100644
--- a/src/app/shared/page.tsx
+++ b/src/app/shared/page.tsx
@@ -40,12 +40,20 @@ function TagFilter({ value, onChange }: { value: string[]; onChange: (v: string[
     return () => document.removeEventListener("mousedown", handler);
   }, []);
 
-  if (!tags.length) return null;
-
-  const toggle = (id: string) =>
-    onChange(value.includes(id) ? value.filter((x) => x !== id) : [...value, id]);
+  const toggle = (id: string) => {
+    let next: string[];
+    if (value.includes(id)) {
+      next = value.filter((x) => x !== id);
+    } else if (id === "untagged") {
+      next = ["untagged"];
+    } else {
+      next = [...value.filter((x) => x !== "untagged"), id];
+    }
+    onChange(next);
+  };
 
   const label = value.length === 0 ? "All Tags"
+    : value.includes("untagged") ? "No tags"
     : value.length === 1 ? (tags.find((t) => String(t.id) === value[0])?.name ?? "1 tag")
     : `${value.length} tags`;
 
@@ -61,6 +69,11 @@ function TagFilter({ value, onChange }: { value: string[]; onChange: (v: string[
       </button>
       {open && (
         <div className="absolute top-full mt-1 z-20 bg-zinc-900 border border-zinc-700 rounded-lg shadow-xl min-w-[160px] max-h-56 overflow-y-auto">
+          <label className="flex items-center gap-2 px-3 py-1.5 hover:bg-zinc-800 cursor-pointer text-sm border-b border-zinc-800">
+            <input type="checkbox" checked={value.includes("untagged")} onChange={() => toggle("untagged")}
+              className="accent-indigo-500 flex-shrink-0" />
+            <span className="text-zinc-400 italic">No tags</span>
+          </label>
           {tags.map((t) => (
             <label key={t.id} className="flex items-center gap-2 px-3 py-1.5 hover:bg-zinc-800 cursor-pointer text-sm">
               <input type="checkbox" checked={value.includes(String(t.id))} onChange={() => toggle(String(t.id))}
@@ -259,8 +272,9 @@ function PaymentHistory({ participantId, currentUserId }: { participantId: numbe
 // ── Main page ─────────────────────────────────────────────────────────────────
 export default function SharedPage() {
   const [tagIds, setTagIds] = useState<string[]>([]);
+  const realTagIds = tagIds.filter((id) => id !== "untagged");
   const { data: transactions = [], isLoading: txLoading } = useSharedTransactions(tagIds);
-  const { data: balances = [], isLoading: balLoading } = useParticipantBalances(tagIds);
+  const { data: balances = [], isLoading: balLoading } = useParticipantBalances(realTagIds);
   const { data: me } = useCurrentUser();
   const [addingParticipant, setAddingParticipant] = useState(false);
   const [paymentModal, setPaymentModal] = useState<{ id: number; name: string; balance: number } | null>(null);
diff --git a/src/app/transactions/page.tsx b/src/app/transactions/page.tsx
index 9826bdd..56a7bb2 100644
--- a/src/app/transactions/page.tsx
+++ b/src/app/transactions/page.tsx
@@ -651,9 +651,14 @@ function TransactionsContent() {
           placeholder="All Banks"
         />
         <MultiSelect
-          options={(tags ?? []).map((t) => ({ value: String(t.id), label: t.name }))}
+          options={[{ value: "untagged", label: "No tags" }, ...(tags ?? []).map((t) => ({ value: String(t.id), label: t.name }))]}
           value={filters.tag_ids}
-          onChange={(v) => setFilters((f) => ({ ...f, tag_ids: v, offset: 0 }))}
+          onChange={(v) => {
+            let next = v;
+            if (v.includes("untagged") && !filters.tag_ids.includes("untagged")) next = ["untagged"];
+            else if (filters.tag_ids.includes("untagged") && v.length > 1) next = v.filter((x) => x !== "untagged");
+            setFilters((f) => ({ ...f, tag_ids: next, offset: 0 }));
+          }}
           placeholder="All Tags"
         />
         <MultiSelect
diff --git a/src/lib/queries.ts b/src/lib/queries.ts
index e43e72b..a11b301 100644
--- a/src/lib/queries.ts
+++ b/src/lib/queries.ts
@@ -115,8 +115,14 @@ export async function getTransactions(ownerId: number, filters: TransactionFilte
     }
   }
   if (filters.tag_ids?.length) {
-    conditions.push(`EXISTS (SELECT 1 FROM transaction_tags tt2 WHERE tt2.transaction_id = t.id AND tt2.tag_id = ANY($${paramIdx++}::int[]))`);
-    params.push(filters.tag_ids.map(Number));
+    const noTags = filters.tag_ids.includes("untagged");
+    const realTagIds = filters.tag_ids.filter((id) => id !== "untagged").map(Number);
+    if (noTags) {
+      conditions.push(`NOT EXISTS (SELECT 1 FROM transaction_tags tt2 WHERE tt2.transaction_id = t.id)`);
+    } else if (realTagIds.length > 0) {
+      conditions.push(`EXISTS (SELECT 1 FROM transaction_tags tt2 WHERE tt2.transaction_id = t.id AND tt2.tag_id = ANY($${paramIdx++}::int[]))`);
+      params.push(realTagIds);
+    }
   }
   if (filters.transaction_types?.length) {
     conditions.push(`t.transaction_type = ANY($${paramIdx++}::text[])`);
@@ -343,10 +349,12 @@ export async function getTags() {
   `);
 }
 
-export async function getSharedTransactions(ownerId: number, tagIds?: number[]) {
+export async function getSharedTransactions(ownerId: number, tagIds?: number[], noTags?: boolean) {
   const params: unknown[] = [ownerId];
   let tagClause = "";
-  if (tagIds?.length) {
+  if (noTags) {
+    tagClause = `AND NOT EXISTS (SELECT 1 FROM transaction_tags tt WHERE tt.transaction_id = t.id)`;
+  } else if (tagIds?.length) {
     params.push(tagIds);
     tagClause = `AND EXISTS (SELECT 1 FROM transaction_tags tt WHERE tt.transaction_id = t.id AND tt.tag_id = ANY($2::int[]))`;
   }