diff --git a/src/otoole/input.py b/src/otoole/input.py
index a9efc11..ff828a7 100644
--- a/src/otoole/input.py
+++ b/src/otoole/input.py
@@ -257,7 +257,7 @@ def write(
         logger.debug(default_values)
 
         self.inputs = inputs  # parameter/set data OR result data
-        input_data = kwargs.get("input_data", None)
+        self.input_params = kwargs.get("input_data", None)  # parameter/set data
 
         for name, df in sorted(self.inputs.items()):
             logger.debug("%s has %s columns: %s", name, len(df.index.names), df.columns)
@@ -271,26 +271,16 @@ def write(
                     raise KeyError("Cannot find %s in input or results config", name)
 
             if entity_type != "set":
-                default_value = default_values[name]
-                # This should be moved inside the loop and performed once for each parameter
-                if self.write_defaults and "Annual" in name:
-                    try:
-                        logger.info(f"Expanding {name} with default values")
-                        df_expand = self._expand_dataframe(
-                            df, default_value, input_data
-                        )
-                    except KeyError as ex:
-                        logger.info(
-                            f"Unable to write default values due to missing {ex} data"
-                        )
+                if self.write_defaults:
+                    df_out = self._expand_dataframe(name, df)
                 else:
-                    df_expand = df
+                    df_out = df
 
                 self._write_parameter(
-                    df_expand,
+                    df_out,
                     name,
                     handle,
-                    default=default_value,
+                    default=default_values[name],
                     input_data=self.inputs,
                 )
             else:
@@ -301,84 +291,62 @@ def write(
         if isinstance(handle, TextIO):
             handle.close()
 
-    def _expand_dataframe(
-        self, data: pd.DataFrame, default: float, input_data: dict[str, pd.DataFrame]
-    ) -> pd.DataFrame:
-        """Expand an individual dataframe with default values"""
-        # save set information for each parameter
-        index_data = {}
-        for index in data.index.names:
-            index_data[index] = input_data[index]["VALUE"].to_list()
-
-        # set index
-        if len(index_data) > 1:
-            new_index = pd.MultiIndex.from_product(
-                list(index_data.values()), names=list(index_data.keys())
-            )
-        else:
-            new_index = pd.Index(
-                list(index_data.values())[0], name=list(index_data.keys())[0]
-            )
-        df_default = pd.DataFrame(index=new_index, dtype="float16")
-
-        # save default result value
-        df_default["VALUE"] = default
-
-        # combine result and default value dataframe
-        if not data.empty:
-            df = pd.concat([data, df_default])
-            df = df[~df.index.duplicated(keep="first")]
-        else:
-            df = df_default
-        df = df.sort_index()
-        return df
-
-    def _expand_defaults(
-        self,
-        inputs: Dict[str, pd.DataFrame],
-        default_values: Dict[str, float],
-        input_data: Dict[str, pd.DataFrame] = None,
-    ) -> Dict[str, pd.DataFrame]:
+    def _expand_dataframe(self, name: str, df: pd.DataFrame) -> Dict[str, pd.DataFrame]:
         """Populates default value entry rows in dataframes
 
         Parameters
         ----------
-        inputs : Dict[str, pd.DataFrame],
-            param/set data or result data
-        default_values : Dict[str, float]
-            defaults of param/result data
-        input_data: Dict[str, pd.DataFrame]
-            param/set data needed for expanding result data
+        name: str
+            Name of parameter/result to expand
+        df: pd.DataFrame,
+            input parameter/result data to be expanded
 
         Returns
         -------
-        Dict[str, pd.DataFrame]
+        pd.DataFrame,
             Input data with expanded default values replacing missing entries
         """
 
-        sets = [x for x in self.user_config if self.user_config[x]["type"] == "set"]
-        input_data = input_data if input_data else inputs.copy()
+        # TODO: Issue with how otoole handles trade route right now.
+        # The double definition of REGION throws an error.
+        if name == "TradeRoute":
+            return df
+
+        default_df = self._get_default_dataframe(name)
 
-        output = {}
-        for name, data in inputs.items():
+        df = pd.concat([df, default_df])
+        df = df[~df.index.duplicated(keep="first")]
+        return df.sort_index()
 
-            # skip sets
-            if name in sets:
-                output[name] = data
-                continue
+        # default_df.update(df)
+        # return default_df.sort_index()
 
-            # TODO
-            # Issue with how otoole handles trade route right now.
-            # The double definition of REGION throws an error.
-            if name == "TradeRoute":
-                output[name] = data
-                continue
+    def _get_default_dataframe(self, name: str) -> pd.DataFrame:
+        """Creates default dataframe"""
+
+        index_data = {}
+        indices = self.user_config[name]["indices"]
+        try:  # result data
+            for index in indices:
+                index_data[index] = self.input_params[index]["VALUE"].to_list()
+        except (TypeError, KeyError):  # parameter data
+            for index in indices:
+                index_data[index] = self.inputs[index]["VALUE"].to_list()
 
-            output[name] = self._expand_dataframe(
-                data, default_values[name], input_data
+        if len(index_data) > 1:
+            new_index = pd.MultiIndex.from_product(
+                list(index_data.values()), names=list(index_data.keys())
+            )
+        else:
+            new_index = pd.Index(
+                list(index_data.values())[0], name=list(index_data.keys())[0]
             )
 
-        return output
+        df = pd.DataFrame(index=new_index)
+        df["VALUE"] = self.default_values[name]
+        df["VALUE"] = df.VALUE.astype(self.user_config[name]["dtype"])
+
+        return df
 
 
 class ReadStrategy(Strategy):