diff --git a/solidity/contracts/lib/interfaces/izeto.sol b/solidity/contracts/lib/interfaces/izeto.sol
index 6b16fc9..a7f1034 100644
--- a/solidity/contracts/lib/interfaces/izeto.sol
+++ b/solidity/contracts/lib/interfaces/izeto.sol
@@ -21,6 +21,7 @@ interface IZeto is IZetoBase {
     event UTXOTransfer(
         uint256[] inputs,
         uint256[] outputs,
-        address indexed submitter
+        address indexed submitter,
+        bytes data
     );
 }
diff --git a/solidity/contracts/zeto_anon.sol b/solidity/contracts/zeto_anon.sol
index 5132462..74b0dc0 100644
--- a/solidity/contracts/zeto_anon.sol
+++ b/solidity/contracts/zeto_anon.sol
@@ -63,7 +63,8 @@ contract Zeto_Anon is IZeto, ZetoBase, ZetoFungibleWithdraw, UUPSUpgradeable {
     function transfer(
         uint256[2] memory inputs,
         uint256[2] memory outputs,
-        Commonlib.Proof calldata proof
+        Commonlib.Proof calldata proof,
+        bytes calldata data
     ) public returns (bool) {
         require(
             validateTransactionProposal(inputs, outputs, proof),
@@ -91,7 +92,7 @@ contract Zeto_Anon is IZeto, ZetoBase, ZetoFungibleWithdraw, UUPSUpgradeable {
             inputArray[i] = inputs[i];
             outputArray[i] = outputs[i];
         }
-        emit UTXOTransfer(inputArray, outputArray, msg.sender);
+        emit UTXOTransfer(inputArray, outputArray, msg.sender, data);
 
         return true;
     }
diff --git a/solidity/contracts/zeto_anon_nullifier.sol b/solidity/contracts/zeto_anon_nullifier.sol
index 2a003dd..144a64f 100644
--- a/solidity/contracts/zeto_anon_nullifier.sol
+++ b/solidity/contracts/zeto_anon_nullifier.sol
@@ -77,7 +77,8 @@ contract Zeto_AnonNullifier is
         uint256[2] memory nullifiers,
         uint256[2] memory outputs,
         uint256 root,
-        Commonlib.Proof calldata proof
+        Commonlib.Proof calldata proof,
+        bytes calldata data
     ) public returns (bool) {
         require(
             validateTransactionProposal(nullifiers, outputs, root),
@@ -108,7 +109,7 @@ contract Zeto_AnonNullifier is
             nullifierArray[i] = nullifiers[i];
             outputArray[i] = outputs[i];
         }
-        emit UTXOTransfer(nullifierArray, outputArray, msg.sender);
+        emit UTXOTransfer(nullifierArray, outputArray, msg.sender, data);
         return true;
     }
 
diff --git a/solidity/contracts/zeto_anon_nullifier_kyc.sol b/solidity/contracts/zeto_anon_nullifier_kyc.sol
index 340ea00..0d5469b 100644
--- a/solidity/contracts/zeto_anon_nullifier_kyc.sol
+++ b/solidity/contracts/zeto_anon_nullifier_kyc.sol
@@ -83,7 +83,8 @@ contract Zeto_AnonNullifierKyc is
         uint256[2] memory nullifiers,
         uint256[2] memory outputs,
         uint256 root,
-        Commonlib.Proof calldata proof
+        Commonlib.Proof calldata proof,
+        bytes calldata data
     ) public returns (bool) {
         require(
             validateTransactionProposal(nullifiers, outputs, root),
@@ -115,7 +116,7 @@ contract Zeto_AnonNullifierKyc is
             nullifierArray[i] = nullifiers[i];
             outputArray[i] = outputs[i];
         }
-        emit UTXOTransfer(nullifierArray, outputArray, msg.sender);
+        emit UTXOTransfer(nullifierArray, outputArray, msg.sender, data);
         return true;
     }
 
diff --git a/solidity/contracts/zeto_nf_anon.sol b/solidity/contracts/zeto_nf_anon.sol
index c8166d8..7424a28 100644
--- a/solidity/contracts/zeto_nf_anon.sol
+++ b/solidity/contracts/zeto_nf_anon.sol
@@ -55,7 +55,8 @@ contract Zeto_NfAnon is IZeto, ZetoBase, UUPSUpgradeable {
     function transfer(
         uint256 input,
         uint256 output,
-        Commonlib.Proof calldata proof
+        Commonlib.Proof calldata proof,
+        bytes calldata data
     ) public returns (bool) {
         require(
             validateTransactionProposal([input, 0], [output, 0], proof),
@@ -81,7 +82,7 @@ contract Zeto_NfAnon is IZeto, ZetoBase, UUPSUpgradeable {
         inputArray[0] = input;
         outputArray[0] = output;
 
-        emit UTXOTransfer(inputArray, outputArray, msg.sender);
+        emit UTXOTransfer(inputArray, outputArray, msg.sender, data);
         return true;
     }
 
diff --git a/solidity/contracts/zeto_nf_anon_nullifier.sol b/solidity/contracts/zeto_nf_anon_nullifier.sol
index 64853af..2a758dd 100644
--- a/solidity/contracts/zeto_nf_anon_nullifier.sol
+++ b/solidity/contracts/zeto_nf_anon_nullifier.sol
@@ -63,7 +63,8 @@ contract Zeto_NfAnonNullifier is IZeto, ZetoNullifier, UUPSUpgradeable {
         uint256 nullifier,
         uint256 output,
         uint256 root,
-        Commonlib.Proof calldata proof
+        Commonlib.Proof calldata proof,
+        bytes calldata data
     ) public returns (bool) {
         require(
             validateTransactionProposal([nullifier, 0], [output, 0], root),
@@ -89,7 +90,7 @@ contract Zeto_NfAnonNullifier is IZeto, ZetoNullifier, UUPSUpgradeable {
         nullifierArray[0] = nullifier;
         outputArray[0] = output;
 
-        emit UTXOTransfer(nullifierArray, outputArray, msg.sender);
+        emit UTXOTransfer(nullifierArray, outputArray, msg.sender, data);
         return true;
     }
 
diff --git a/solidity/contracts/zkDvP.sol b/solidity/contracts/zkDvP.sol
index bf47aa6..a36d2f9 100644
--- a/solidity/contracts/zkDvP.sol
+++ b/solidity/contracts/zkDvP.sol
@@ -220,7 +220,8 @@ contract zkDvP {
                 paymentToken.transfer(
                     trade.paymentInputs,
                     trade.paymentOutputs,
-                    trade.paymentProof
+                    trade.paymentProof,
+                    ""
                 ),
                 "Payment branch of the trade failed"
             );
@@ -228,7 +229,8 @@ contract zkDvP {
                 assetToken.transfer(
                     trade.assetInput,
                     trade.assetOutput,
-                    trade.assetProof
+                    trade.assetProof,
+                    ""
                 ),
                 "Asset branch of the trade failed"
             );
diff --git a/solidity/test/zeto_anon.ts b/solidity/test/zeto_anon.ts
index 4a1a043..765a94c 100644
--- a/solidity/test/zeto_anon.ts
+++ b/solidity/test/zeto_anon.ts
@@ -221,7 +221,9 @@ describe("Zeto based fungible token with anonymity without encryption or nullifi
     encodedProof: any
   ) {
     const signerAddress = await signer.signer.getAddress();
-    const tx = await zeto.connect(signer.signer).transfer(inputCommitments, outputCommitments, encodedProof);
+    const tx = await zeto
+      .connect(signer.signer)
+      .transfer(inputCommitments, outputCommitments, encodedProof, "0x");
     const results = await tx.wait();
     console.log(`Method transfer() complete. Gas used: ${results?.gasUsed}`);
 
diff --git a/solidity/test/zeto_anon_nullifier.ts b/solidity/test/zeto_anon_nullifier.ts
index 04b0ed5..82bbee4 100644
--- a/solidity/test/zeto_anon_nullifier.ts
+++ b/solidity/test/zeto_anon_nullifier.ts
@@ -404,7 +404,9 @@ describe("Zeto based fungible token with anonymity using nullifiers without encr
     encodedProof: any
   ) {
     const startTx = Date.now();
-    const tx = await zeto.connect(signer.signer).transfer(nullifiers, outputCommitments, root, encodedProof);
+    const tx = await zeto
+      .connect(signer.signer)
+      .transfer(nullifiers, outputCommitments, root, encodedProof, "0x");
     const results: ContractTransactionReceipt | null = await tx.wait();
     console.log(`Time to execute transaction: ${Date.now() - startTx}ms. Gas used: ${results?.gasUsed}`);
     return results;
diff --git a/solidity/test/zeto_anon_nullifier_kyc.ts b/solidity/test/zeto_anon_nullifier_kyc.ts
index c33bf9d..3abaf07 100644
--- a/solidity/test/zeto_anon_nullifier_kyc.ts
+++ b/solidity/test/zeto_anon_nullifier_kyc.ts
@@ -582,7 +582,9 @@ describe("Zeto based fungible token with anonymity, KYC, using nullifiers withou
     encodedProof: any
   ) {
     const startTx = Date.now();
-    const tx = await zeto.connect(signer.signer).transfer(nullifiers, outputCommitments, root, encodedProof);
+    const tx = await zeto
+      .connect(signer.signer)
+      .transfer(nullifiers, outputCommitments, root, encodedProof, "0x");
     const results: ContractTransactionReceipt | null = await tx.wait();
     console.log(`Time to execute transaction: ${Date.now() - startTx}ms. Gas used: ${results?.gasUsed}`);
     return results;
diff --git a/solidity/test/zeto_nf_anon.ts b/solidity/test/zeto_nf_anon.ts
index 543fae0..c514609 100644
--- a/solidity/test/zeto_nf_anon.ts
+++ b/solidity/test/zeto_nf_anon.ts
@@ -126,7 +126,9 @@ describe("Zeto based non-fungible token with anonymity without encryption or nul
     outputCommitment: BigNumberish,
     encodedProof: any
   ) {
-    const tx = await zeto.connect(signer.signer).transfer(inputCommitment, outputCommitment, encodedProof);
+    const tx = await zeto
+      .connect(signer.signer)
+      .transfer(inputCommitment, outputCommitment, encodedProof, "0x");
     const results = await tx.wait();
     console.log(`Method transfer() complete. Gas used: ${results?.gasUsed}`);
 
diff --git a/solidity/test/zeto_nf_anon_nullifier.ts b/solidity/test/zeto_nf_anon_nullifier.ts
index 8b2a33f..f721e66 100644
--- a/solidity/test/zeto_nf_anon_nullifier.ts
+++ b/solidity/test/zeto_nf_anon_nullifier.ts
@@ -264,7 +264,9 @@ describe("Zeto based non-fungible token with anonymity using nullifiers without
     encodedProof: any
   ) {
     const startTx = Date.now();
-    const tx = await zeto.connect(signer.signer).transfer(nullifier, outputCommitment, root, encodedProof);
+    const tx = await zeto
+      .connect(signer.signer)
+      .transfer(nullifier, outputCommitment, root, encodedProof, "0x");
     const results: ContractTransactionReceipt | null = await tx.wait();
     console.log(`Time to execute transaction: ${Date.now() - startTx}ms. Gas used: ${results?.gasUsed}`);
     return results;