diff --git a/nchs_mortality/.gitignore b/nchs_mortality/.gitignore
index d98285328..344822e5b 100644
--- a/nchs_mortality/.gitignore
+++ b/nchs_mortality/.gitignore
@@ -5,6 +5,9 @@ params.json
 
 # Do not commit output files
 receiving/*.csv
+daily_receiving/*.csv
+cache/*.csv
+daily_cache/*.csv
 
 # Do not commit test files
 tests/receiving/*.csv
diff --git a/nchs_mortality/delphi_nchs_mortality/run.py b/nchs_mortality/delphi_nchs_mortality/run.py
index ec5416bb2..b8a7832d4 100644
--- a/nchs_mortality/delphi_nchs_mortality/run.py
+++ b/nchs_mortality/delphi_nchs_mortality/run.py
@@ -9,7 +9,7 @@
 from typing import Dict, Any
 
 import numpy as np
-from delphi_utils import S3ArchiveDiffer, get_structured_logger, create_export_csv
+from delphi_utils import S3ArchiveDiffer, get_structured_logger, create_export_csv, Nans
 
 from .archive_diffs import arch_diffs
 from .constants import (METRICS, SENSOR_NAME_MAP,
@@ -17,6 +17,18 @@
 from .pull import pull_nchs_mortality_data
 
 
+def add_nancodes(df):
+    """Add nancodes to the dataframe."""
+    # Default missingness codes
+    df["missing_val"] = Nans.NOT_MISSING
+    df["missing_se"] = Nans.NOT_APPLICABLE
+    df["missing_sample_size"] = Nans.NOT_APPLICABLE
+
+    # Mark any remaining nans with unknown
+    remaining_nans_mask = df["val"].isnull()
+    df.loc[remaining_nans_mask, "missing_val"] = Nans.OTHER
+    return df
+
 def run_module(params: Dict[str, Any]):
     """Run module for processing NCHS mortality data.
 
@@ -67,7 +79,8 @@ def run_module(params: Dict[str, Any]):
             df["val"] = df[metric]
             df["se"] = np.nan
             df["sample_size"] = np.nan
-            df = df[~df["val"].isnull()]
+            df = add_nancodes(df)
+            # df = df[~df["val"].isnull()]
             sensor_name = "_".join([SENSOR_NAME_MAP[metric]])
             dates = create_export_csv(
                 df,
@@ -91,7 +104,8 @@ def run_module(params: Dict[str, Any]):
                     df["val"] = df[metric] / df["population"] * INCIDENCE_BASE
                 df["se"] = np.nan
                 df["sample_size"] = np.nan
-                df = df[~df["val"].isnull()]
+                df = add_nancodes(df)
+                # df = df[~df["val"].isnull()]
                 sensor_name = "_".join([SENSOR_NAME_MAP[metric], sensor])
                 dates = create_export_csv(
                     df,
diff --git a/nchs_mortality/tests/test_run.py b/nchs_mortality/tests/test_run.py
index 36dba6698..b842bd4c1 100644
--- a/nchs_mortality/tests/test_run.py
+++ b/nchs_mortality/tests/test_run.py
@@ -60,4 +60,8 @@ def test_output_file_format(self, run_as_module, date):
             df = pd.read_csv(
                 join(output_folder, "weekly_202026_state_deaths_covid_incidence_prop.csv")
             )
-            assert (df.columns.values == ["geo_id", "val", "se", "sample_size"]).all()
+            expected_columns = [
+                "geo_id", "val", "se", "sample_size",
+                "missing_val", "missing_se", "missing_sample_size"
+            ]
+            assert (df.columns.values == expected_columns).all()