diff --git a/src/finance.adb b/src/finance.adb
new file mode 100644
index 0000000..c24cf91
--- /dev/null
+++ b/src/finance.adb
@@ -0,0 +1,28 @@
+package body Finance is
+
+   function Round (N : Decimal) return Decimal is
+   begin
+      return N;
+   end Round;
+
+   procedure Add_Entry
+     (Trans : in out Transaction;
+      E : Transaction_Entry)
+   is
+   begin
+      Trans.Entries.Append (E);
+   end Add_Entry;
+
+   function Validate (T : Transaction)
+     return Boolean
+   is
+      Sum : Decimal := 0.0;
+   begin
+      for E of T.Entries loop
+         Sum := @ + E.Amount;
+      end loop;
+
+      return Round (Sum) = 0.0;
+   end Validate;
+
+end Finance;
diff --git a/src/finance.ads b/src/finance.ads
new file mode 100644
index 0000000..5dfadd4
--- /dev/null
+++ b/src/finance.ads
@@ -0,0 +1,35 @@
+with Ada.Containers.Vectors;
+with Ada.Strings.Unbounded; use Ada.Strings.Unbounded;
+
+package Finance is
+
+   type Decimal is delta 1.0E-20 digits 38;
+
+   type Transaction_Entry is
+      record
+         Amount : Decimal;
+         Account : Unbounded_String;
+      end record;
+
+   package Entry_Vec is new Ada.Containers.Vectors (
+      Index_Type => Natural, 
+      Element_Type => Transaction_Entry
+   );
+
+   use type Entry_Vec.Vector;
+
+   type Transaction is
+      record
+         Entries : Entry_Vec.Vector;
+      end record;
+
+   function Round (N : Decimal) return Decimal;
+
+   procedure Add_Entry
+     (Trans : in out Transaction;
+      E : Transaction_Entry);
+
+   function Validate (T : Transaction)
+     return Boolean;
+
+end Finance;