diff --git a/src/Web/Stripe/Error.hs b/src/Web/Stripe/Error.hs
--- a/src/Web/Stripe/Error.hs
+++ b/src/Web/Stripe/Error.hs
@@ -1,4 +1,5 @@
-{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE OverloadedStrings  #-}
 -- |
 -- Module      : Web.Stripe.Error
 -- Copyright   : (c) David Johnson, 2014
@@ -14,9 +15,11 @@
     ) where
 
 import           Control.Applicative ((<$>))
+import           Control.Exception
+import           Control.Monad       (mzero)
 import           Data.Aeson
 import           Data.Text           (Text)
-import           Control.Monad       (mzero)
+import           Data.Typeable
 
 ------------------------------------------------------------------------------
 -- | Error Codes for HTTP Responses
@@ -27,7 +30,7 @@
         | NotFound          -- ^ 404
         | StripeServerError -- ^ (>=500)
         | UnknownHTTPCode   -- ^ All other codes
-          deriving Show
+          deriving (Show, Typeable)
 
 ------------------------------------------------------------------------------
 -- | Stripe Error Types
@@ -38,7 +41,7 @@
         | ConnectionFailure
         | ParseFailure
         | UnknownErrorType
-          deriving Show
+          deriving (Show, Typeable)
 
 ------------------------------------------------------------------------------
 -- | Stripe Error Codes
@@ -56,7 +59,7 @@
         | ProcessingError
         | RateLimit
         | UnknownError
-          deriving Show
+          deriving (Show, Typeable)
 
 ------------------------------------------------------------------------------
 -- | Stripe Error
@@ -66,7 +69,9 @@
     , errorCode  :: Maybe StripeErrorCode
     , errorParam :: Maybe Text
     , errorHTTP  :: Maybe StripeErrorHTTPCode
-    } deriving Show
+    } deriving (Show, Typeable)
+
+instance Exception StripeError
 
 ------------------------------------------------------------------------------
 -- | Parses an error message into a `StripeErrorType`
diff --git a/src/Web/Stripe/StripeRequest.hs b/src/Web/Stripe/StripeRequest.hs
--- a/src/Web/Stripe/StripeRequest.hs
+++ b/src/Web/Stripe/StripeRequest.hs
@@ -68,7 +68,8 @@
                                      RefundApplicationFee(..), RefundReason(..),
                                      RoutingNumber(..), StartingAfter(..),
                                      StatementDescription(..), Source(..),
-                                     SubscriptionId(..), TaxID(..), TimeRange(..),
+                                     SubscriptionId(..), TaxID(..), 
+                                     TaxPercent(..), TimeRange(..),
                                      TokenId(..), TransactionId(..),
                                      TransactionType(..), TransferId(..),
                                      TransferStatus(..), TrialEnd(..),
@@ -163,7 +164,7 @@
 
 instance ToStripeParam AtPeriodEnd where
   toStripeParam (AtPeriodEnd p) =
-    (("prorate", if p then "true" else "false") :)
+    (("at_period_end", if p then "true" else "false") :)
 
 instance ToStripeParam BankAccountId where
   toStripeParam (BankAccountId bid) =
@@ -374,6 +375,10 @@
 instance ToStripeParam TaxID where
   toStripeParam (TaxID tid) =
     (("tax_id", Text.encodeUtf8 tid) :)
+
+instance ToStripeParam TaxPercent where
+  toStripeParam (TaxPercent tax) =
+    (("tax_percent", fromString $ showFFloat (Just 2) tax "") :)
 
 instance ToStripeParam a => ToStripeParam (TimeRange a) where
   toStripeParam (TimeRange{..}) =
diff --git a/src/Web/Stripe/Subscription.hs b/src/Web/Stripe/Subscription.hs
--- a/src/Web/Stripe/Subscription.hs
+++ b/src/Web/Stripe/Subscription.hs
@@ -69,6 +69,7 @@
     , Subscription       (..)
     , SubscriptionId     (..)
     , SubscriptionStatus (..)
+    , TaxPercent         (..)
     , TrialEnd           (..)
     ) where
 
@@ -86,7 +87,8 @@
                                              StartingAfter(..),
                                              Subscription (..), StripeList(..),
                                              SubscriptionId (..),
-                                             SubscriptionStatus (..), TrialEnd(..))
+                                             SubscriptionStatus (..), TaxPercent(..), 
+                                             TrialEnd(..))
 import           Web.Stripe.Types.Util      (getCustomerId)
 
 ------------------------------------------------------------------------------
@@ -110,6 +112,7 @@
 instance StripeHasParam CreateSubscription Quantity
 instance StripeHasParam CreateSubscription ApplicationFeePercent
 instance StripeHasParam CreateSubscription MetaData
+instance StripeHasParam CreateSubscription TaxPercent
 
 ------------------------------------------------------------------------------
 -- | Retrieve a `Subscription` by `CustomerId` and `SubscriptionId`
@@ -154,6 +157,7 @@
 instance StripeHasParam UpdateSubscription Quantity
 instance StripeHasParam UpdateSubscription ApplicationFeePercent
 instance StripeHasParam UpdateSubscription MetaData
+instance StripeHasParam UpdateSubscription TaxPercent
 
 ------------------------------------------------------------------------------
 -- | Delete a `Subscription` by `CustomerId` and `SubscriptionId`
diff --git a/src/Web/Stripe/Types.hs b/src/Web/Stripe/Types.hs
--- a/src/Web/Stripe/Types.hs
+++ b/src/Web/Stripe/Types.hs
@@ -557,6 +557,7 @@
     , subscriptionApplicationFeePercent :: Maybe Double
     , subscriptionDiscount              :: Maybe Discount
     , subscriptionMetaData              :: MetaData
+    , subscriptionTaxPercent            :: Maybe Double
 } deriving (Read, Show, Eq, Ord, Data, Typeable)
 
 ------------------------------------------------------------------------------
@@ -580,6 +581,7 @@
                     <*> o .:? "application_fee_percent"
                     <*> o .:? "discount"
                     <*> o .: "metadata"
+                    <*> o .:? "tax_percent"
    parseJSON _ = mzero
 
 ------------------------------------------------------------------------------
@@ -601,6 +603,11 @@
    parseJSON (String "canceled") = pure Canceled
    parseJSON (String "unpaid")   = pure UnPaid
    parseJSON _                   = mzero
+
+------------------------------------------------------------------------------
+-- | `TaxPercent` for a `Subscription`
+newtype TaxPercent = TaxPercent Double deriving (Read, Show, Eq, Ord, Data, Typeable)
+
 
 ------------------------------------------------------------------------------
 -- | `PlanId` for a `Plan`
diff --git a/stripe-core.cabal b/stripe-core.cabal
--- a/stripe-core.cabal
+++ b/stripe-core.cabal
@@ -1,5 +1,5 @@
 name:                stripe-core
-version:             2.0.3
+version:             2.1.0
 synopsis:            Stripe API for Haskell - Pure Core
 license:             MIT
 license-file:        LICENSE
@@ -25,8 +25,8 @@
                      , bytestring           >= 0.10  && < 0.11
                      , mtl                  >= 2.1.2 && < 2.3
                      , text                 >= 1.0   && < 1.3
-                     , time                 >= 1.4   && < 1.6
-                     , transformers         >= 0.3   && < 0.5
+                     , time                 >= 1.4   && < 1.7
+                     , transformers         >= 0.3   && < 0.6
                      , unordered-containers >= 0.2.5 && < 0.3
 
   default-language:    Haskell2010