diff --git a/onadata/libs/utils/common_tags.py b/onadata/libs/utils/common_tags.py
index 5c097e5960..81b5298e1a 100644
--- a/onadata/libs/utils/common_tags.py
+++ b/onadata/libs/utils/common_tags.py
@@ -71,7 +71,8 @@
 # datetime format that we store in mongo
 MONGO_STRFTIME = "%Y-%m-%dT%H:%M:%S"
 DATE_FORMAT = "%Y-%m-%d"
-KNOWN_DATE_FORMATS = [MONGO_STRFTIME, DATE_FORMAT, "%Y-%m-%dT%H:%M:%S.%f%z"]
+ISO_FORMAT = "%Y-%m-%dT%H:%M:%S.%f%z"
+KNOWN_DATE_FORMATS = [MONGO_STRFTIME, DATE_FORMAT, ISO_FORMAT]
 
 # how to represent N/A in exports
 NA_REP = "n/a"