diff --git a/src/lisvap/utils/writers.py b/src/lisvap/utils/writers.py
index 998b3b5..d7e86c7 100644
--- a/src/lisvap/utils/writers.py
+++ b/src/lisvap/utils/writers.py
@@ -78,6 +78,9 @@ def get_output_parameters_monthly(start_date, timestep, time_frequency, timestep
         output_index = 0
     elif current_date == last_date_last_month:
         filename_suffix = day_inside_last_month.strftime('%Y%m')
+        first_date_last_month = day_inside_last_month.replace(day=1) + datetime.timedelta(seconds=(2 * timestep_stride))
+        num_steps_done_in_last_month = int((last_date_last_month - first_date_last_month).total_seconds() / timestep_stride) + 1
+        output_index = num_steps_done_in_last_month
     elif current_output_index >= num_steps_done_in_current_month:
         output_index = num_steps_done_in_current_month - 1
     return filename_suffix, output_index
@@ -98,6 +101,9 @@ def get_output_parameters_yearly(start_date, timestep, time_frequency, timestep_
         output_index = 0
     elif current_date == last_date_last_year:
         filename_suffix = day_inside_last_year.strftime('%Y')
+        first_date_last_year = first_date_current_year.replace(year=current_date.year - 1)
+        num_steps_done_in_last_year = int((last_date_last_year - first_date_last_year).total_seconds() / timestep_stride) + 1
+        output_index = num_steps_done_in_last_year - 1
     elif current_output_index >= num_steps_done_in_current_year:
         output_index = num_steps_done_in_current_year - 1
     return filename_suffix, output_index