diff --git a/src/routes/settings.import.tsx b/src/routes/settings.import.tsx
index f1e3e47..224ab6e 100644
--- a/src/routes/settings.import.tsx
+++ b/src/routes/settings.import.tsx
@@ -1372,6 +1372,16 @@ function ImportPage() {
         }
       }
 
+      // Inserts must have a non-null client_id; fall back to placeholder
+      // ONLY for genuinely new invoices that never matched anything.
+      let placeholderClient: string | null = null;
+      const insertsNeedingClient = toInsertInv.filter((r) => !r.client_id);
+      if (insertsNeedingClient.length > 0) {
+        placeholderClient = await ensureArchivedClient("Imported (no client)", "imported-no-client");
+        if (placeholderClient) {
+          for (const r of insertsNeedingClient) r.client_id = placeholderClient;
+        }
+      }
       for (let k = 0; k < toInsertInv.length; k += chunkSize) {
         const slice = toInsertInv.slice(k, k + chunkSize);
         const { data, error } = await supabase.from("invoices").insert(slice as any).select("*");