diff --git a/internal/ethapi/transaction_args.go b/internal/ethapi/transaction_args.go
index 1032d067f1..3ecc384210 100644
--- a/internal/ethapi/transaction_args.go
+++ b/internal/ethapi/transaction_args.go
@@ -42,6 +42,7 @@ import (
 type TransactionArgs struct {
 	From                 *common.Address `json:"from"`
 	To                   *common.Address `json:"to"`
+	Type                 *hexutil.Uint64 `json:"type,omitempty"`
 	Gas                  *hexutil.Uint64 `json:"gas"`
 	GasPrice             *hexutil.Big    `json:"gasPrice"`
 	MaxFeePerGas         *hexutil.Big    `json:"maxFeePerGas"`
@@ -101,6 +102,9 @@ type sidecarConfig struct {
 
 // setDefaults fills in default values for unspecified tx fields.
 func (args *TransactionArgs) setDefaults(ctx context.Context, b Backend, config sidecarConfig) error {
+	if err := args.validateTxTypeSupported(); err != nil {
+		return err
+	}
 	if err := args.setBlobTxSidecar(ctx, config); err != nil {
 		return err
 	}
@@ -176,6 +180,9 @@ func (args *TransactionArgs) setDefaults(ctx context.Context, b Backend, config
 	} else {
 		args.ChainID = (*hexutil.Big)(want)
 	}
+	if err := args.validateTxTypeMatch(types.LegacyTxType); err != nil {
+		return err
+	}
 	return nil
 }
 
@@ -390,6 +397,9 @@ func (args *TransactionArgs) setBlobTxSidecar(ctx context.Context, config sideca
 // CallDefaults sanitizes the transaction arguments, often filling in zero values,
 // for the purpose of eth_call class of RPC methods.
 func (args *TransactionArgs) CallDefaults(globalGasCap uint64, baseFee *big.Int, chainID *big.Int) error {
+	if err := args.validateTxTypeSupported(); err != nil {
+		return err
+	}
 	// Reject invalid combinations of pre- and post-1559 fee styles
 	if args.GasPrice != nil && (args.MaxFeePerGas != nil || args.MaxPriorityFeePerGas != nil) {
 		return errors.New("both gasPrice and (maxFeePerGas or maxPriorityFeePerGas) specified")
@@ -436,10 +446,40 @@ func (args *TransactionArgs) CallDefaults(globalGasCap uint64, baseFee *big.Int,
 	if args.BlobFeeCap == nil && args.BlobHashes != nil {
 		args.BlobFeeCap = new(hexutil.Big)
 	}
+	if err := args.validateTxTypeMatch(types.LegacyTxType); err != nil {
+		return err
+	}
 
 	return nil
 }
 
+func (args *TransactionArgs) validateTxTypeSupported() error {
+	if args.Type == nil {
+		return nil
+	}
+	switch uint64(*args.Type) {
+	case types.LegacyTxType, types.AccessListTxType, types.DynamicFeeTxType, types.BlobTxType, types.SetCodeTxType:
+		return nil
+	default:
+		return fmt.Errorf("unsupported transaction type: %d", uint64(*args.Type))
+	}
+}
+
+func (args *TransactionArgs) validateTxTypeMatch(defaultType int) error {
+	if args.Type == nil {
+		return nil
+	}
+	// Blob txs cannot be contract creations. ToTransaction assumes this invariant.
+	if args.BlobHashes != nil && args.To == nil {
+		return errors.New(`missing "to" in blob transaction`)
+	}
+	inferred := args.ToTransaction(defaultType).Type()
+	if uint64(*args.Type) != uint64(inferred) {
+		return fmt.Errorf("transaction type mismatch (requested=%d inferred=%d)", uint64(*args.Type), inferred)
+	}
+	return nil
+}
+
 // ToMessage converts the transaction arguments to the Message type used by the
 // core evm. This method is used in calls and traces that do not require a real
 // live transaction.
diff --git a/internal/ethapi/transaction_args_test.go b/internal/ethapi/transaction_args_test.go
index ccb46a810d..20ff039368 100644
--- a/internal/ethapi/transaction_args_test.go
+++ b/internal/ethapi/transaction_args_test.go
@@ -256,6 +256,79 @@ func TestSetFeeDefaults(t *testing.T) {
 	}
 }
 
+func TestTransactionArgsRejectUnsupportedTypeInCallDefaults(t *testing.T) {
+	t.Parallel()
+
+	badType := hexutil.Uint64(0x5)
+	args := &TransactionArgs{Type: &badType}
+	err := args.CallDefaults(0, big.NewInt(1), big.NewInt(1))
+	if err == nil {
+		t.Fatal("expected error for unsupported transaction type")
+	}
+	if err.Error() != "unsupported transaction type: 5" {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func TestTransactionArgsRejectUnsupportedTypeInSetDefaults(t *testing.T) {
+	t.Parallel()
+
+	badType := hexutil.Uint64(0x5)
+	gas := hexutil.Uint64(21000)
+	to := common.Address{0x1}
+	args := &TransactionArgs{
+		To:   &to,
+		Gas:  &gas,
+		Type: &badType,
+	}
+	err := args.setDefaults(context.Background(), newBackendMock(), sidecarConfig{})
+	if err == nil {
+		t.Fatal("expected error for unsupported transaction type")
+	}
+	if err.Error() != "unsupported transaction type: 5" {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func TestTransactionArgsRejectTypeMismatchInCallDefaults(t *testing.T) {
+	t.Parallel()
+
+	requestedLegacy := hexutil.Uint64(types.LegacyTxType)
+	args := &TransactionArgs{
+		Type:        &requestedLegacy,
+		MaxFeePerGas: (*hexutil.Big)(big.NewInt(2)),
+	}
+	err := args.CallDefaults(0, big.NewInt(1), big.NewInt(1))
+	if err == nil {
+		t.Fatal("expected type mismatch error")
+	}
+	if err.Error() != "transaction type mismatch (requested=0 inferred=2)" {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func TestTransactionArgsRejectTypeMismatchInSetDefaults(t *testing.T) {
+	t.Parallel()
+
+	requestedDynamic := hexutil.Uint64(types.DynamicFeeTxType)
+	gas := hexutil.Uint64(21000)
+	gasPrice := (*hexutil.Big)(big.NewInt(1))
+	to := common.Address{0x1}
+	args := &TransactionArgs{
+		To:       &to,
+		Gas:      &gas,
+		GasPrice: gasPrice,
+		Type:     &requestedDynamic,
+	}
+	err := args.setDefaults(context.Background(), newBackendMock(), sidecarConfig{})
+	if err == nil {
+		t.Fatal("expected type mismatch error")
+	}
+	if err.Error() != "transaction type mismatch (requested=2 inferred=0)" {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
 type backendMock struct {
 	current *types.Header
 	config  *params.ChainConfig