diff --git a/errors/common.go b/errors/common.go
index 8c152c4493..8eb05045d3 100644
--- a/errors/common.go
+++ b/errors/common.go
@@ -8,6 +8,7 @@ import (
 	"fmt"
 
 	abci "github.com/tendermint/abci/types"
+	"github.com/tendermint/basecoin"
 )
 
 const (
@@ -26,8 +27,14 @@ const (
 	msgTooManySignatures = "Too many signatures"
 	msgNoChain           = "No chain id provided"
 	msgWrongChain        = "Tx belongs to different chain - %s"
+	msgUnknownTxType     = "We cannot handle this tx - %v"
 )
 
+func UnknownTxType(tx basecoin.Tx) TMError {
+	msg := fmt.Sprintf(msgUnknownTxType, tx)
+	return New(msg, abci.CodeType_UnknownRequest)
+}
+
 func InternalError(msg string) TMError {
 	return New(msg, abci.CodeType_InternalError)
 }
diff --git a/modules/coin/handler.go b/modules/coin/handler.go
new file mode 100644
index 0000000000..de66c434a6
--- /dev/null
+++ b/modules/coin/handler.go
@@ -0,0 +1,64 @@
+package coin
+
+import (
+	"github.com/tendermint/basecoin"
+	"github.com/tendermint/basecoin/errors"
+	"github.com/tendermint/basecoin/types"
+)
+
+const (
+	NameCoin = "coin"
+)
+
+// Handler writes
+type Handler struct{}
+
+var _ basecoin.Handler = Handler{}
+
+func (_ Handler) Name() string {
+	return NameCoin
+}
+
+// CheckTx checks if there is enough money in the account
+func (h Handler) CheckTx(ctx basecoin.Context, store types.KVStore, tx basecoin.Tx) (res basecoin.Result, err error) {
+	_, err = checkTx(ctx, tx)
+	if err != nil {
+		return res, err
+	}
+
+	// now make sure there is money
+
+	// otherwise, we are good
+	return res, nil
+}
+
+// DeliverTx moves the money
+func (h Handler) DeliverTx(ctx basecoin.Context, store types.KVStore, tx basecoin.Tx) (res basecoin.Result, err error) {
+	_, err = checkTx(ctx, tx)
+	if err != nil {
+		return res, err
+	}
+
+	// now move the money
+	return basecoin.Result{}, nil
+}
+
+func checkTx(ctx basecoin.Context, tx basecoin.Tx) (*SendTx, error) {
+	// check if the tx is proper type and valid
+	send, ok := tx.Unwrap().(*SendTx)
+	if !ok {
+		return nil, errors.UnknownTxType(tx)
+	}
+	err := send.ValidateBasic()
+	if err != nil {
+		return nil, err
+	}
+
+	// check if all inputs have permission
+	for _, in := range send.Inputs {
+		if !ctx.HasPermission(in.Address) {
+			return nil, errors.Unauthorized()
+		}
+	}
+	return send, nil
+}
diff --git a/modules/coin/tx.go b/modules/coin/tx.go
index 1c3b2efb17..935b34bc84 100644
--- a/modules/coin/tx.go
+++ b/modules/coin/tx.go
@@ -98,15 +98,23 @@ func (tx SendTx) ValidateBasic() error {
 	if len(tx.Outputs) == 0 {
 		return errors.NoOutputs()
 	}
+	// make sure all inputs and outputs are individually valid
+	var totalIn, totalOut types.Coins
 	for _, in := range tx.Inputs {
 		if err := in.ValidateBasic(); err != nil {
 			return err
 		}
+		totalIn.Plus(in.Coins)
 	}
 	for _, out := range tx.Outputs {
 		if err := out.ValidateBasic(); err != nil {
 			return err
 		}
+		totalOut.Plus(out.Coins)
+	}
+	// make sure inputs and outputs match
+	if !totalIn.IsEqual(totalOut) {
+		return errors.InvalidCoins()
 	}
 	return nil
 }
diff --git a/stack/multiplexer.go b/stack/multiplexer.go
index 7788fbdd1a..b0cddfc98e 100644
--- a/stack/multiplexer.go
+++ b/stack/multiplexer.go
@@ -1,9 +1,13 @@
 package stack
 
 import (
+	"strings"
+
 	"github.com/tendermint/basecoin"
 	"github.com/tendermint/basecoin/txs"
 	"github.com/tendermint/basecoin/types"
+	wire "github.com/tendermint/go-wire"
+	"github.com/tendermint/go-wire/data"
 )
 
 const (
@@ -45,7 +49,17 @@ func runAll(ctx basecoin.Context, store types.KVStore, txs []basecoin.Tx, next b
 	return combine(rs), nil
 }
 
-func combine(res []basecoin.Result) basecoin.Result {
-	// TODO: how to combine???
-	return res[0]
+// combines all data bytes as a go-wire array.
+// joins all log messages with \n
+func combine(all []basecoin.Result) basecoin.Result {
+	datas := make([]data.Bytes, len(all))
+	logs := make([]string, len(all))
+	for i, r := range all {
+		datas[i] = r.Data
+		logs[i] = r.Log
+	}
+	return basecoin.Result{
+		Data: wire.BinaryBytes(datas),
+		Log:  strings.Join(logs, "\n"),
+	}
 }