diff --git a/conservancy_beancount/ranges.py b/conservancy_beancount/ranges.py
new file mode 100644
index 0000000000000000000000000000000000000000..aa2348b7fe8fdf6af4e94accdaaf7b9af41ef271
--- /dev/null
+++ b/conservancy_beancount/ranges.py
@@ -0,0 +1,59 @@
+"""ranges.py - Higher-typed range classes"""
+# Copyright © 2020  Brett Smith
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+import datetime
+
+from decimal import Decimal
+
+from typing import (
+    Generic,
+    TypeVar,
+    Union,
+)
+
+RangeT = TypeVar(
+    'RangeT',
+    # This is a relatively arbitrary set of types. Feel free to add to it if
+    # you need; the types just need to support enough comparisons to implement
+    # _GenericRange.__contains__.
+    datetime.date,
+    datetime.datetime,
+    datetime.time,
+    Union[int, Decimal],
+)
+
+class _GenericRange(Generic[RangeT]):
+    """range for higher-level types
+
+    This class knows how to check membership for higher-level types just like
+    Python's built-in range. It does not know how to iterate or step.
+    """
+    def __init__(self, start: RangeT, stop: RangeT) -> None:
+        self.start: RangeT = start
+        self.stop: RangeT = stop
+
+    def __repr__(self) -> str:
+        return "{clsname}({self.start!r}, {self.stop!r})".format(
+            clsname=type(self).__name__,
+            self=self,
+        )
+
+    def __contains__(self, item: RangeT) -> bool:
+        return self.start <= item < self.stop
+
+
+DateRange = _GenericRange[datetime.date]
+DecimalCompatRange = _GenericRange[Union[int, Decimal]]