diff --git a/routes/status.js b/routes/status.js
index a3c1b06..455ab40 100644
--- a/routes/status.js
+++ b/routes/status.js
@@ -18,6 +18,20 @@ function errorMessage(err) {
   return err?.message || String(err);
 }
 
+// SQLite stores datetime('now') as "YYYY-MM-DD HH:MM:SS" (UTC, no Z).
+// Without the Z suffix, JS Date parses it as LOCAL time, creating timezone
+// inconsistencies when mixed with ISO strings that do have Z.
+// This ensures all timestamps sent to clients are unambiguous UTC ISO strings.
+function toIso(sqliteOrIso) {
+  if (!sqliteOrIso) return null;
+  const s = String(sqliteOrIso).trim();
+  // Already ISO with Z or offset — return as-is
+  if (s.includes('T') && (s.endsWith('Z') || s.match(/[+-]\d{2}:\d{2}$/))) return s;
+  // SQLite format "YYYY-MM-DD HH:MM:SS" — append Z to declare it UTC
+  if (/^\d{4}-\d{2}-\d{2}[ T]\d{2}:\d{2}/.test(s)) return s.replace(' ', 'T') + 'Z';
+  return s;
+}
+
 function monthRange(now) {
   const year = now.getFullYear();
   const month = now.getMonth() + 1;
@@ -291,7 +305,7 @@ router.get('/', async (req, res) => {
         source_count: sourceRow.source_count ?? 0,
         account_count: accountRow.account_count ?? 0,
         transaction_count: txRow.transaction_count ?? 0,
-        last_sync_at: sourceRow.last_sync_at || null,
+        last_sync_at: toIso(sourceRow.last_sync_at),
         last_error: errorRow?.last_error || null,
       };
     }
@@ -305,7 +319,7 @@ router.get('/', async (req, res) => {
     const raw = getSetting('cleanup_last_result');
     cleanup = {
       ok: true,
-      last_run_at: getSetting('cleanup_last_run_at') || null,
+      last_run_at: toIso(getSetting('cleanup_last_run_at')),
       last_result: raw ? JSON.parse(raw) : null,
     };
   } catch { /* non-fatal */ }