diff --git a/src/Purrse.Api/Services/ChatService.cs b/src/Purrse.Api/Services/ChatService.cs
index ee64b93..cca00d3 100644
--- a/src/Purrse.Api/Services/ChatService.cs
+++ b/src/Purrse.Api/Services/ChatService.cs
@@ -473,7 +473,7 @@ public class ChatService : IChatService
 
     private async Task<(string, object, string)> ExecuteGetSpendingByCategoryAsync(Guid userId, Dictionary<string, object> args)
     {
-        var startDate = ParseDateArg(args, "start_date") ?? new DateTime(DateTime.UtcNow.Year, DateTime.UtcNow.Month, 1);
+        var startDate = ParseDateArg(args, "start_date") ?? new DateTime(DateTime.UtcNow.Year, DateTime.UtcNow.Month, 1, 0, 0, 0, DateTimeKind.Utc);
         var endDate = ParseDateArg(args, "end_date") ?? DateTime.UtcNow;
 
         var report = await _reportService.GetSpendingByCategoryAsync(userId, startDate, endDate);
@@ -714,7 +714,8 @@ public class ChatService : IChatService
     {
         var str = ParseStringArg(args, key);
         if (str == null) return null;
-        return DateTime.TryParse(str, out var dt) ? dt : null;
+        if (!DateTime.TryParse(str, out var dt)) return null;
+        return DateTime.SpecifyKind(dt, DateTimeKind.Utc);
     }
 
     private static Guid? ParseGuidArg(Dictionary<string, object> args, string key)