diff --git a/src/routes/settings.import.tsx b/src/routes/settings.import.tsx
index b96df37..2eca362 100644
--- a/src/routes/settings.import.tsx
+++ b/src/routes/settings.import.tsx
@@ -1055,6 +1055,31 @@ function ImportPage() {
       return;
     }
 
+    // For cases: assign sequential "YYYY-####" numbers to any row missing a
+    // case_number, continuing from the highest existing number for the year.
+    if (cfg.table === "cases") {
+      const year = new Date().getFullYear();
+      const prefix = `${year}-`;
+      const { data: existing } = await supabase
+        .from("cases")
+        .select("case_number")
+        .like("case_number", `${prefix}%`);
+      let maxSeq = 0;
+      for (const row of (existing ?? []) as Array<{ case_number: string | null }>) {
+        const m = /^(\d{4})-(\d+)$/.exec(String(row.case_number ?? ""));
+        if (m && m[1] === String(year)) {
+          const n = parseInt(m[2], 10);
+          if (Number.isFinite(n) && n > maxSeq) maxSeq = n;
+        }
+      }
+      for (const r of mapped) {
+        if (!r.case_number || !String(r.case_number).trim()) {
+          maxSeq += 1;
+          r.case_number = `${prefix}${String(maxSeq).padStart(4, "0")}`;
+        }
+      }
+    }
+
     // Batch upsert in chunks of 200
     const chunkSize = 200;
     let inserted = 0;