diff --git a/db/statedb/statedb.go b/db/statedb/statedb.go
index 3113982..c9b1a31 100644
--- a/db/statedb/statedb.go
+++ b/db/statedb/statedb.go
@@ -201,95 +201,73 @@ func (s *StateDB) GetAccount(idx common.Idx) (*common.Account, error) {
 	return common.AccountFromBytes(b)
 }
 
-// CreateAccount creates a new Account in the StateDB for the given Idx.
-// MerkleTree is not affected.
-func (s *StateDB) CreateAccount(idx common.Idx, account *common.Account) error {
+// CreateAccount creates a new Account in the StateDB for the given Idx.  If
+// StateDB.mt==nil, MerkleTree is not affected, otherwise updates the
+// MerkleTree, returning a CircomProcessorProof.
+func (s *StateDB) CreateAccount(idx common.Idx, account *common.Account) (*merkletree.CircomProcessorProof, error) {
 	// store at the DB the key: v, and value: leaf.Bytes()
 	v, err := account.HashValue()
 	if err != nil {
-		return err
+		return nil, err
 	}
 	accountBytes, err := account.Bytes()
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	// store the Leaf value
 	tx, err := s.db.NewTx()
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	_, err = tx.Get(idx.Bytes())
 	if err != db.ErrNotFound {
-		return ErrAccountAlreadyExists
+		return nil, ErrAccountAlreadyExists
 	}
 
 	tx.Put(v.Bytes(), accountBytes[:])
 	tx.Put(idx.Bytes(), v.Bytes())
 
-	return tx.Commit()
+	if err := tx.Commit(); err != nil {
+		return nil, err
+	}
+
+	if s.mt != nil {
+		return s.mt.AddAndGetCircomProof(idx.BigInt(), v)
+	}
+	return nil, nil
 }
 
-// UpdateAccount updates the Account in the StateDB for the given Idx.
-// MerkleTree is not affected.
-func (s *StateDB) UpdateAccount(idx common.Idx, account *common.Account) error {
+// UpdateAccount updates the Account in the StateDB for the given Idx.  If
+// StateDB.mt==nil, MerkleTree is not affected, otherwise updates the
+// MerkleTree, returning a CircomProcessorProof.
+func (s *StateDB) UpdateAccount(idx common.Idx, account *common.Account) (*merkletree.CircomProcessorProof, error) {
 	// store at the DB the key: v, and value: leaf.Bytes()
 	v, err := account.HashValue()
 	if err != nil {
-		return err
+		return nil, err
 	}
 	accountBytes, err := account.Bytes()
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	tx, err := s.db.NewTx()
 	if err != nil {
-		return err
+		return nil, err
 	}
 	tx.Put(v.Bytes(), accountBytes[:])
 	tx.Put(idx.Bytes(), v.Bytes())
 
-	return tx.Commit()
-}
-
-// MTCreateAccount creates a new Account in the StateDB for the given Idx,
-// and updates the MerkleTree, returning a CircomProcessorProof
-func (s *StateDB) MTCreateAccount(idx common.Idx, account *common.Account) (*merkletree.CircomProcessorProof, error) {
-	if s.mt == nil {
-		return nil, ErrStateDBWithoutMT
-	}
-	err := s.CreateAccount(idx, account)
-	if err != nil {
-		return nil, err
-	}
-
-	v, err := account.HashValue() // already computed in s.CreateAccount, next iteration reuse first computation
-	if err != nil {
-		return nil, err
-	}
-	// Add k & v into the MT
-	return s.mt.AddAndGetCircomProof(idx.BigInt(), v)
-}
-
-// MTUpdateAccount updates the Account in the StateDB for the given Idx, and
-// updates the MerkleTree, returning a CircomProcessorProof
-func (s *StateDB) MTUpdateAccount(idx common.Idx, account *common.Account) (*merkletree.CircomProcessorProof, error) {
-	if s.mt == nil {
-		return nil, ErrStateDBWithoutMT
-	}
-	err := s.UpdateAccount(idx, account)
-	if err != nil {
+	if err := tx.Commit(); err != nil {
 		return nil, err
 	}
 
-	v, err := account.HashValue() // already computed in s.CreateAccount, next iteration reuse first computation
-	if err != nil {
-		return nil, err
+	if s.mt != nil {
+		return s.mt.Update(idx.BigInt(), v)
 	}
-	// Add k & v into the MT
-	return s.mt.Update(idx.BigInt(), v)
+	return nil, nil
 }
 
 // MTGetProof returns the CircomVerifierProof for a given Idx
diff --git a/db/statedb/statedb_test.go b/db/statedb/statedb_test.go
index 96e8cd8..60c558e 100644
--- a/db/statedb/statedb_test.go
+++ b/db/statedb/statedb_test.go
@@ -55,7 +55,7 @@ func TestStateDBWithoutMT(t *testing.T) {
 
 	// add test accounts
 	for i := 0; i < len(accounts); i++ {
-		err = sdb.CreateAccount(common.Idx(i), accounts[i])
+		_, err = sdb.CreateAccount(common.Idx(i), accounts[i])
 		assert.Nil(t, err)
 	}
 
@@ -68,26 +68,17 @@ func TestStateDBWithoutMT(t *testing.T) {
 	// try already existing idx and get error
 	_, err = sdb.GetAccount(common.Idx(1)) // check that exist
 	assert.Nil(t, err)
-	err = sdb.CreateAccount(common.Idx(1), accounts[1]) // check that can not be created twice
+	_, err = sdb.CreateAccount(common.Idx(1), accounts[1]) // check that can not be created twice
 	assert.NotNil(t, err)
 	assert.Equal(t, ErrAccountAlreadyExists, err)
 
 	// update accounts
 	for i := 0; i < len(accounts); i++ {
 		accounts[i].Nonce = accounts[i].Nonce + 1
-		err = sdb.UpdateAccount(common.Idx(i), accounts[i])
+		_, err = sdb.UpdateAccount(common.Idx(i), accounts[i])
 		assert.Nil(t, err)
 	}
 
-	// check that can not call MerkleTree methods of the StateDB
-	_, err = sdb.MTCreateAccount(common.Idx(1), accounts[1])
-	assert.NotNil(t, err)
-	assert.Equal(t, ErrStateDBWithoutMT, err)
-
-	_, err = sdb.MTUpdateAccount(common.Idx(1), accounts[1])
-	assert.NotNil(t, err)
-	assert.Equal(t, ErrStateDBWithoutMT, err)
-
 	_, err = sdb.MTGetProof(common.Idx(1))
 	assert.NotNil(t, err)
 	assert.Equal(t, ErrStateDBWithoutMT, err)
@@ -113,7 +104,7 @@ func TestStateDBWithMT(t *testing.T) {
 
 	// add test accounts
 	for i := 0; i < len(accounts); i++ {
-		_, err = sdb.MTCreateAccount(common.Idx(i), accounts[i])
+		_, err = sdb.CreateAccount(common.Idx(i), accounts[i])
 		assert.Nil(t, err)
 	}
 
@@ -126,7 +117,7 @@ func TestStateDBWithMT(t *testing.T) {
 	// try already existing idx and get error
 	_, err = sdb.GetAccount(common.Idx(1)) // check that exist
 	assert.Nil(t, err)
-	_, err = sdb.MTCreateAccount(common.Idx(1), accounts[1]) // check that can not be created twice
+	_, err = sdb.CreateAccount(common.Idx(1), accounts[1]) // check that can not be created twice
 	assert.NotNil(t, err)
 	assert.Equal(t, ErrAccountAlreadyExists, err)
 
@@ -136,7 +127,7 @@ func TestStateDBWithMT(t *testing.T) {
 	// update accounts
 	for i := 0; i < len(accounts); i++ {
 		accounts[i].Nonce = accounts[i].Nonce + 1
-		_, err = sdb.MTUpdateAccount(common.Idx(i), accounts[i])
+		_, err = sdb.UpdateAccount(common.Idx(i), accounts[i])
 		assert.Nil(t, err)
 	}
 	a, err := sdb.GetAccount(common.Idx(1)) // check that account value has been updated
@@ -159,7 +150,7 @@ func TestCheckpoints(t *testing.T) {
 
 	// add test accounts
 	for i := 0; i < len(accounts); i++ {
-		_, err = sdb.MTCreateAccount(common.Idx(i), accounts[i])
+		_, err = sdb.CreateAccount(common.Idx(i), accounts[i])
 		assert.Nil(t, err)
 	}
 
diff --git a/db/statedb/txprocessors.go b/db/statedb/txprocessors.go
index a0148ad..14180ea 100644
--- a/db/statedb/txprocessors.go
+++ b/db/statedb/txprocessors.go
@@ -89,7 +89,7 @@ func (s *StateDB) applyCreateAccount(tx *common.L1Tx) error {
 		EthAddr:   tx.FromEthAddr,
 	}
 
-	err := s.CreateAccount(common.Idx(s.idx+1), account)
+	_, err := s.CreateAccount(common.Idx(s.idx+1), account)
 	if err != nil {
 		return err
 	}
@@ -120,13 +120,13 @@ func (s *StateDB) applyDeposit(tx *common.L1Tx, transfer bool) error {
 		// add amount to the receiver
 		accReceiver.Balance = new(big.Int).Add(accReceiver.Balance, tx.Amount)
 		// update receiver account in localStateDB
-		err = s.UpdateAccount(tx.ToIdx, accReceiver)
+		_, err = s.UpdateAccount(tx.ToIdx, accReceiver)
 		if err != nil {
 			return err
 		}
 	}
 	// update sender account in localStateDB
-	err = s.UpdateAccount(tx.FromIdx, accSender)
+	_, err = s.UpdateAccount(tx.FromIdx, accSender)
 	if err != nil {
 		return err
 	}
@@ -146,18 +146,21 @@ func (s *StateDB) applyTransfer(tx *common.Tx) error {
 		return err
 	}
 
+	// increment nonce
+	accSender.Nonce++
+
 	// substract amount to the sender
 	accSender.Balance = new(big.Int).Sub(accSender.Balance, tx.Amount)
 	// add amount to the receiver
 	accReceiver.Balance = new(big.Int).Add(accReceiver.Balance, tx.Amount)
 
 	// update receiver account in localStateDB
-	err = s.UpdateAccount(tx.ToIdx, accReceiver)
+	_, err = s.UpdateAccount(tx.ToIdx, accReceiver)
 	if err != nil {
 		return err
 	}
 	// update sender account in localStateDB
-	err = s.UpdateAccount(tx.FromIdx, accSender)
+	_, err = s.UpdateAccount(tx.FromIdx, accSender)
 	if err != nil {
 		return err
 	}