diff --git a/spanner_orm/field.py b/spanner_orm/field.py
index 64f40c6..733130a 100644
--- a/spanner_orm/field.py
+++ b/spanner_orm/field.py
@@ -48,16 +48,27 @@ class Field(object):
   def __init__(self,
                field_type: Type[FieldType],
                nullable: bool = False,
-               primary_key: bool = False):
+               primary_key: bool = False,
+               allow_commit_timestamp: bool = False):
     self.name = None
     self._type = field_type
     self._nullable = nullable
     self._primary_key = primary_key
+    self._allow_commit_timestamp = allow_commit_timestamp
+
+    if self._type.ddl() != "TIMESTAMP" and self._allow_commit_timestamp:
+      raise error.ValidationError('allow_commit_timestamp can not be set on field {}'.format(self._type))
 
   def ddl(self) -> str:
     if self._nullable:
-      return self._type.ddl()
-    return '{field_type} NOT NULL'.format(field_type=self._type.ddl())
+      nullable = ''
+    else:
+      nullable = ' NOT NULL'
+    if self._allow_commit_timestamp:
+      options = ' OPTIONS (allow_commit_timestamp=true)'
+    else:
+      options = ''
+    return '{field_type}{nullable}{options}'.format(field_type=self._type.ddl(), nullable=nullable, options=options)
 
   def field_type(self) -> Type[FieldType]:
     return self._type
diff --git a/spanner_orm/tests/models.py b/spanner_orm/tests/models.py
index 2a8218a..19f8ef4 100644
--- a/spanner_orm/tests/models.py
+++ b/spanner_orm/tests/models.py
@@ -76,6 +76,7 @@ class UnittestModel(model.Model):
   string = field.Field(field.String, primary_key=True)
   string_2 = field.Field(field.String, nullable=True)
   timestamp = field.Field(field.Timestamp)
+  timestamp_2 = field.Field(field.Timestamp, nullable=True, allow_commit_timestamp=True)
   string_array = field.Field(field.StringArray, nullable=True)
 
   test_index = index.Index(['string_2'])
diff --git a/spanner_orm/tests/update_test.py b/spanner_orm/tests/update_test.py
index 7b55965..f12bae5 100644
--- a/spanner_orm/tests/update_test.py
+++ b/spanner_orm/tests/update_test.py
@@ -67,8 +67,9 @@ def test_create_table(self, get_model):
 
     test_model_ddl = ('CREATE TABLE table (int_ INT64 NOT NULL, int_2 INT64,'
                       ' string STRING(MAX) NOT NULL, string_2 STRING(MAX),'
-                      ' timestamp TIMESTAMP NOT NULL, string_array'
-                      ' ARRAY<STRING(MAX)>) PRIMARY KEY (int_, string)')
+                      ' timestamp TIMESTAMP NOT NULL,'
+                      ' timestamp_2 TIMESTAMP OPTIONS (allow_commit_timestamp=true),'
+                      ' string_array ARRAY<STRING(MAX)>) PRIMARY KEY (int_, string)')
     self.assertEqual(test_update.ddl(), test_model_ddl)
 
   @mock.patch('spanner_orm.admin.metadata.SpannerMetadata.model')