diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,13 @@
+# Version [0.4.0.0](https://github.com/blockfrost/blockfrost-haskell/compare/v0.3.1.0...v0.4.0.0) (2022-03-09)
+
+* Changes
+  * `AccountInfo`
+    * `activeEpoch` field type changed from `Integer` to `Maybe Integer`
+  * `UtxoInput`
+    * `txHash` field type changed from `Text` to `TxHash` newtype
+  * `TxMetaJSON` and `TxMetaCBOR`
+    * `txHash` field type changed from `Text` to `TxHash` newtype
+
 # Version [0.3.1.0](https://github.com/blockfrost/blockfrost-haskell/compare/v0.3.0.0...v0.3.1.0) (2022-02-17)
 
 * Additions
diff --git a/blockfrost-api.cabal b/blockfrost-api.cabal
--- a/blockfrost-api.cabal
+++ b/blockfrost-api.cabal
@@ -1,6 +1,6 @@
 cabal-version:       2.2
 name:                blockfrost-api
-version:             0.3.1.0
+version:             0.4.0.0
 synopsis:            API definitions for blockfrost.io
 description:         Core types and Servant API description
 homepage:            https://github.com/blockfrost/blockfrost-haskell
diff --git a/src/Blockfrost/Types/Cardano/Accounts.hs b/src/Blockfrost/Types/Cardano/Accounts.hs
--- a/src/Blockfrost/Types/Cardano/Accounts.hs
+++ b/src/Blockfrost/Types/Cardano/Accounts.hs
@@ -20,7 +20,7 @@
 data AccountInfo = AccountInfo
   { _accountInfoStakeAddress       :: Address -- ^ Bech32 stake address
   , _accountInfoActive             :: Bool -- ^ Registration state of an account
-  , _accountInfoActiveEpoch        :: Integer -- ^ Epoch of the most recent action - registration or deregistration
+  , _accountInfoActiveEpoch        :: Maybe Integer -- ^ Epoch of the most recent action - registration or deregistration
   , _accountInfoControlledAmount   :: Lovelaces  -- ^ Balance of the account in Lovelaces
   , _accountInfoRewardsSum         :: Lovelaces -- ^ Sum of all funds rewards for the account in the Lovelaces
   , _accountInfoWithdrawalsSum     :: Lovelaces -- ^ Sum of all the withdrawals for the account in the Lovelaces
@@ -37,7 +37,7 @@
   toSamples = pure $ singleSample $ AccountInfo
     { _accountInfoStakeAddress = "stake1ux3g2c9dx2nhhehyrezyxpkstartcqmu9hk63qgfkccw5rqttygt7"
     , _accountInfoActive = True
-    , _accountInfoActiveEpoch = 412
+    , _accountInfoActiveEpoch = pure 412
     , _accountInfoControlledAmount = 619154618165
     , _accountInfoRewardsSum = 319154618165
     , _accountInfoWithdrawalsSum = 12125369253
diff --git a/src/Blockfrost/Types/Cardano/Metadata.hs b/src/Blockfrost/Types/Cardano/Metadata.hs
--- a/src/Blockfrost/Types/Cardano/Metadata.hs
+++ b/src/Blockfrost/Types/Cardano/Metadata.hs
@@ -32,7 +32,7 @@
 
 -- | Transaction metadata content in JSON
 data TxMetaJSON = TxMetaJSON
-  { _txMetaJSONTxHash       :: Text -- ^ Transaction hash that contains the specific metadata
+  { _txMetaJSONTxHash       :: TxHash -- ^ Transaction hash that contains the specific metadata
   , _txMetaJSONJSONMetadata :: Maybe Value -- ^ Content of the JSON metadata
   }
   deriving stock (Show, Eq, Generic)
@@ -62,7 +62,7 @@
 
 -- | Transaction metadata content in CBOR
 data TxMetaCBOR = TxMetaCBOR
-  { _txMetaCBORTxHash   :: Text -- ^ Transaction hash that contains the specific metadata
+  { _txMetaCBORTxHash   :: TxHash -- ^ Transaction hash that contains the specific metadata
   , _txMetaCBORMetadata :: Maybe Text -- ^ Content of the CBOR metadata
   }
   deriving stock (Show, Eq, Generic)
diff --git a/src/Blockfrost/Types/Cardano/Transactions.hs b/src/Blockfrost/Types/Cardano/Transactions.hs
--- a/src/Blockfrost/Types/Cardano/Transactions.hs
+++ b/src/Blockfrost/Types/Cardano/Transactions.hs
@@ -86,7 +86,7 @@
 data UtxoInput = UtxoInput
   { _utxoInputAddress     :: Address -- ^ Input address
   , _utxoInputAmount      :: [Amount]
-  , _utxoInputTxHash      :: Text -- ^ Hash of the UTXO transaction
+  , _utxoInputTxHash      :: TxHash -- ^ Hash of the UTXO transaction
   , _utxoInputOutputIndex :: Integer -- ^ UTXO index in the transaction
   , _utxoInputCollateral  :: Bool -- ^ UTXO is a script collateral input
   , _utxoInputDataHash    :: Maybe DatumHash -- ^ The hash of the transaction output datum
diff --git a/test/Cardano/Accounts.hs b/test/Cardano/Accounts.hs
--- a/test/Cardano/Accounts.hs
+++ b/test/Cardano/Accounts.hs
@@ -75,7 +75,7 @@
 accountExpected = AccountInfo
     { _accountInfoStakeAddress = "stake1ux3g2c9dx2nhhehyrezyxpkstartcqmu9hk63qgfkccw5rqttygt7"
     , _accountInfoActive = True
-    , _accountInfoActiveEpoch = 412
+    , _accountInfoActiveEpoch = pure 412
     , _accountInfoControlledAmount = 619154618165
     , _accountInfoRewardsSum = 319154618165
     , _accountInfoWithdrawalsSum = 12125369253