diff --git a/lib/WebGUI/Shop/Tax.pm b/lib/WebGUI/Shop/Tax.pm
index d5faccc9d..64b4fcd46 100644
--- a/lib/WebGUI/Shop/Tax.pm
+++ b/lib/WebGUI/Shop/Tax.pm
@@ -87,10 +87,9 @@ Calculate the tax for the contents of the cart.
 sub calculate {
     my $self = shift;
     my $cart = shift;
-
     WebGUI::Error::InvalidParam->throw(error => 'Must pass in a WebGUI::Shop::Cart object')
         unless ref($cart) eq 'WebGUI::Shop::Cart';
-    return $id;
+    return;
 }
 
 #-------------------------------------------------------------------
diff --git a/t/Shop/Tax.t b/t/Shop/Tax.t
index 3a62ae8ed..e264462ec 100644
--- a/t/Shop/Tax.t
+++ b/t/Shop/Tax.t
@@ -31,7 +31,7 @@ my $session         = WebGUI::Test->session;
 #----------------------------------------------------------------------------
 # Tests
 
-my $tests = 62;
+my $tests = 64;
 plan tests => 1 + $tests;
 
 #----------------------------------------------------------------------------
@@ -366,6 +366,19 @@ cmp_deeply(
     'importTaxData: error handling for file that that cannot be read',
 );
 
+#######################################################################
+#
+# calculate
+#
+#######################################################################
+
+eval { $taxer->calculate(); };
+$e = Exception::Class->caught();
+isa_ok($e, 'WebGUI::Error::InvalidParam', 'calculate: error handling for not sending a cart');
+is($e->error, 'Must pass in a WebGUI::Shop::Cart object', 'calculate: error handling for not sending a cart');
+
+##Build a cart, add some Donation SKUs to it.  Set one to be taxable.
+
 }
 
 sub _grabTaxData {
@@ -378,12 +391,6 @@ sub _grabTaxData {
     return @taxData;
 }
 
-#######################################################################
-#
-# calculate
-#
-#######################################################################
-
 #----------------------------------------------------------------------------
 # Cleanup
 END {